close

Вход

Забыли?

вход по аккаунту

?

Heart rate of the dog following autonomic denervation.

код для вставкиСкачать
HEART R A T E O F THE DOG FOLLOWING
AUTONOMIC D E N E R V A T I O N
1). 12.1. TJONG, R. C . TRUEX, K. R. FRTEI)MAK",
4ND
A. K. OTSEN
s. J. PHILLIPS '
Drpartmrnts of Anato?tiii, Xriiroauigrry, and the Cardzovaac~ilarInstitute,
Hahnr niann Mrdrcal G o l l ~ g e ,Phzlatl~lphza,Prvcns?ilonnza
SIX FIGIJRES
The meclianism and control of the lieart beat has stimulated scientific interest and curiosity for hundreds of years.
Numerous studies have been directed to both the intrinsic
conduction system of tlw lieart, and tlic role of the incoming
fibers of tlie autonomic nervous system. 4 wide variety of
technics have been employed by investigators from many
fields (i.e., Anatomy, Pli&iacology, Physiology, Zoology and
the clinical sciences). Despite tlie many ingenious methods
employed, the precise role of the autonomic nervous system
on the lieart still remains a disputed issue. The respective
roles of the sympathetic and parasympathetic nerve fibers to
the heart were of particular interest to the authors, for such
knowledge is of fundanierital and clinical significance. We
were impressed particularly by the lack of agreement in the
literature as to which of the extrinsic cardiac nerves were
responsible for inhihition and acceleration of the heart.
The Webers' (1845) demonstration of cardiac inhibition
followiiig stimulation of the vagus nerve, pioneered an experimental approach that has continued to the present day.
E'owelin (18.51) sooii noted a marked increase in the lieart
rate after bilateral vagotomy, while the presence of acceleraSuppox ted by 1 cseaicli gralits froiii tlie Routlieastern ('liaptcr of the Pcii~isylwiiia Heart Association ; the U. S. Pu1)lic Health Service (H-1595) and tlic
Carcliovnscular Iiistitute of tlic Hnliiienia~inik1edic:il College (I1 2 0 0 3 ) .
' A PI Cdoctoial Fellow of the IT. 8. Puhlic Iie:iltli Sci ricc.
73
tor fil)el*s in the vagus nerve w~isfirst proposed by Scliiff
(1849). The existence of cardioaccclcrator fihcrs in the vagus
licrve of scvoral aniiiials lias since been substantiated by
ILUII~CYOUH
investigators (Hunt am1 Hai.rington, 1897 ; Jourtlan
and S o w a k , '36 ; Ri.ouli;i, Oaniion ant1 Dill, '36 ; Rroulla ant1
Son.ak, '39 ; Broulia, 9 o \ w k aiid Dill, '39 ; Kabat, '40 ; Okinaka,
Nal;ao, Iltcdo aiitl Shizuiiic, '51). An important contribution
~ IXowak
~
( '34) WIS that
cwiitaiiied in tlie 1.cpoi.t of J O L U ~and
the cardioinhibitor fibers u'cre witliin the accessory nerve
rootlets that later joinrtl the vagus, whcreas the cardioaccelerator fibers issucd from the brain stmi only ill the rootlets of
the vagus nerve. This obscrvatioii has also been confirrrietl hy
n i m y others.
K ~ o i i k , l+'c~i*gusoii,Jlargaria arid 1,olaiicl ( '36) rccortlctl
action potciitials f i'o~iitlic cardiac syriipathetic i 1 e r v q aiicl
iiotctl a continuous discliargc of irripulscs illolig thc. syni1)atlictic I)i*nnchcs to tlic. liwrt. However, it remains a moot
question as to the rcspectivc iiurril)ei~arid significance of the
caj.tlio~iccclcl.ato1.~lcrator filwrs tliat a1.e within citlioi* tlic vagus or
b"
hy1q)~Itllt
't'1c n(?1'ves.
Tlie Iirart ratc of aiiiiiials following dencrvatioii lius also
I)ceii st udicd by several iiivcstigators. Such studies indicated
tliat after syrriy,atlicctoriiy, tlic heart of ail animal behaved
cwciiti:illy tlic sarric as tliat of il normal intact one. (Sarritiaii,
':34n,l) ; ~ I u i * p l i y'42
, ; ESSCS,
H e i ~ i c kXaiiii
,
and Kalclcs, 43a,b).
f l o \ i ~ ( ~ hilatcral
<~r,
vagotoniy proclneotl pi.ofountl cliaiigcs iii
cai'clioAccelC~t~tioiI,
aiitl the ahility of the animals to pcrforni
with cacrcisc (Sjiiiiiatiii, ':34a,l) ; and If3sscx et al., '43a,h). The
(4fccth of c ~ s c ~ i ~ con
i s ca~giwup of dogs with 1)ilatci.al vagotomy,
M'CIX tlic same i i s a. gr oup with coriipletcbly clc~iioivatetlhcarts
( ESWSct al., '43a,l)). T l i ~IaCtci. iiivestigators stutlietl the
cffccts of csercise illltl atmpiiicl o j i tlic coi.oiiary I)lootl floxv,
1icvti.t i * t i t t b :ind blooci I)iwsiit'e of ti-aiiird dogs.
(lasscr aiitl Rlcck ( '14) ~ ~ c p o ~ ttlic
c t lavrrage heart ratc of
i ~ s t i n gnornial dogs as 109 Ijeats pcr minute (raligc 75 to 140
beats prr niinute). Sariitian ( '34a,b) observed an average
licinrt rate of 90 lwiits ~ W niiiiiif('
Y
(luring quiet staiidiiig of
CAEDIAC DENERVATION
75
clogs (ra1igc 75 to 140 beats). Nurphy ( '42) secured data on
the. basal heart rate of dogs trained t o lie quietly for 60
minutes. IIe reported tlic average hasal lieart rate of 24 dogs
as 50 to 56 heats per rriiiiute (range of -1.2 t o 65 beats per
minute).
All of the above 1icai.t rates were obtained by counting the
pulse rate after varying resting intervals. Truer;, Scott, Long
and Sriiythc ( '5.5) used clcctrocardiogra-1I,hic equipnieiit to
determine the average heart rate of ncw1)orn and young
puppicx T h y observed an average heart rate of 240 beats
p r minute in newborn animals. Horwitz, Spanicr and Wiggem ('33) used similar equipment and reported a nicaii lieart
rate of 121 beats per niiiiutc in 30 adult dogs (range 72 t o 162
I)clats per iniiiutc).
The present study was deviscd to obtain uiiifoi*rn electrocarcliograpliic data on tlie hasal licart rate of adult dogs prior
to, and after selective clcncrvation cxperinients. It was our
Iiopc that data ol)taincd in this coninioii laboratory animal
rriight also pi~ovitlteadtlitiorial iiifoimation that woulcl clarify
tlic rcspcxtivc roles of t boe sympathetic arid parasynipathctic
cardiac n(-~rvcs.h histologic study of such clencrvatcd hearts
is plaiine(1 as a sequel to, hut not a part of, thc present comniunic*
<It'1011.
A1ET 11() I ) S
Two emhalnietl aclult dogs were clisscctetl grossly with the
aid of a large rriagnifying lcns t o clctcrmine the coursc and
i*clatioiisof the iiei*ves entei.iiig iii to the caidiac plexus. After
hc~eoniingfarniliar with thc cervical anatomy of the dog and
the neural conipoiiciits to its lieart, W P obtaiiicd GO adult
moiigrc.1 dogs, 42 rrialcs and 18 fcmalcs. The animals ranged
f ~ * o r 13.3
n
kg to 35.0 kg body weight. 9 c w (logs were allowed
to adjust to tlic cnvii*oiirriciitof the animal colony for a period
of two wccks. I n this intc~*valtlic dogs i~cceivedveterinary
C L I I T to clirriiiiatc all iiifections, distemper, and parasitic
infestations. No attempt \\'as made to train the dogs for the
cxperirncnts ~ l c s c r i l ~ chelow.
d
76
LONG, 1‘111JEX, FILIEDMANN, OLSEN AND PHILLIPS
811 apparatus was designed t o cllirninate distracting visual,
olfactory, and auditory stimuli ancl to make the animals cornfortuble at all times. Extimicous iioiscs and auditory stiniuli
~ v e r creduced to a riiiiiirriurn by cotton ear plugs, while a
specially constructed box clirninatcd visual stimuli. To obviate
the clogs, acute smscl of srnell, a f a n was placed behind the
ariiitial a i d directrtl toward the observer and rcxording
iiisti*uiiiciits. Thus thc) ol)scrver w a s always “downwind”
f i w r t i tlio aiiiinal. Room terripcrature was niaintainoil at 73”
to 80°F. Special tahles were constructed to secure the licart
i a t e in ;L relaxed anirnal. Each table top was constructed of
ciuiv:as and cushioned with foam rubber. Four holes pcrrnittetl
the legs to pass through the top. The paws rested on, ancl were
looscly secured t o an adjustable platform. The animal could
c~itlierlie oil the canvas top, o r stand on the platform Limb
lcatls lvere then placed 011 tlicl legs, and records were matle by
a hot stylus on a direct writing elc.ctrocardiograph. This
ititlspciisive appaixtus u ~ i sufficient
s
to attain hasul contlitioiis.
b”
ISX PERTM F: N T 1
I l e t e r m i w i t i o n of btrsccl lietrrt rccte
Sixty animals werc ustd t o obtain basal heart rate data.
Tlic l m a l ~ c c o r t lof each animal s c w d as its own control,
if the animal was used f o r subsequent dencrvatioit study.
Rectal body teiiipcratni.e was recorded at the start and tcrniiitatioii of each clxpcrinicnt. Elcctrocai.diograpl1 iworcls
i v ( ~ i xthen
~
made, and repeated at 30 minute intervals, f o r a
total period of I20 minutes. Five runs were made on each aniriiul ; each run w a s of 120 rniiiutcs dui-atioii. Lirnl) lead I1 was
iisctl f o r all routiiic. i.ccords, although leads I, 111, AVR, AVL
a i d AVE’ W‘CI’C also included at either the 90 o r 120 minute iiiterval. As thc W G i ~ ~ o was
r d continued at the 120 iiiin~itc
interval, the thermometer was again inserted ant1 tlic aiiimal
sti-nclr lightly on the hindquarters. The effect of t l m c t\yo
stiitiuli uyion tlic i - c ~ o iw~als thus obtainctl.
CARDIAC DRNERVATION
77
H e a r t rate was determined from the average El-R intervals
(10 to 15 consecutive heart beats) a t each 30 minute interval.
After the data for all dogs was collated, the average R-R
intervals were converted t o lieart beats per rninute to insure
2-lccuracy arid minimize errors of conversion.
E X PI!! I t 1M E S ‘1’ 2
Ilcnrt rate nftor sytirputhectomy
Niiieteeii of the anirrials in experinieiit 1 were subjected to
surgical sympathectoniy. This two stage procedure included
a bilateral renioval of the stellate ganglia and the 8 upper
thoracic ganglia. of thc sympathetic trunks. Electrocardiograpliic rccords were made at regular postoperative intclrvals.
EXPERTMEKT 3
Tlenrt r o t F o f tcr 1 v g e c t owiy
Fifteen dogs were subjected to high ccrvical vagectomy.
Tlie vagi were severed bilaterally in one stage. To avoid
b”
wgeneration, a large segment (5 to 6 em) was removed from
c a d i nerve. The proximal aiicl distal stumps were then turned
upon therriselvcs and ligated douhly. Consiclerable postoperative clifficulticls were encountered in these animals. Additional
surgical proceclures were used to elirriinatc pu1monai.y and
gastrointestinal distress, arid continuous iiursing care was
directed toward their dietary and electrolyte requirements.
Electrocai*diogi~apliic
records \yere made on all 15 anirrials for
a period of 6 days.
EXPERIMENT 4
€Teart r a t e a f t e r sprpcrthectorny a.nd i v g e c t o w y
Nine dogs were used in this combined dencrvation experirneiit (experiment 2 in addition t o experiment 3). The caudal
cei*vical gaiigliori was also removed in these animals. Postoperative electi.ocardiograpllic records were ohtainecl on all
9 animals for a period of 7 days.
Pig. 1 1)rnwiiig of the autonomic nervcx tlirit forin the c.nrclincplcrus of the dog heart. Xotc*
tho proximal and dixtril rclntionxliipx of tlic v:igw :ind Hympathctic nerve fibers in this nnimnl.
* Iiidicntcs Lr:inoliioctii,liulic artery nucl II high cardiac. nerve from tbe left nnd right recurrent
lnrpgeal nerves.
78
79
CARDIAC: DENERVATION
12ESLr I i TS
Thct iritriiisic nerves t o tlie caiiiiit. lit1ai.t 1i:ivc 1 ) ~ ~iiitlicatccl
ii
hy diagrams in several of tlic textbooks 011 Comparativc~
Anatomy. Ho\vever, such diagrams ~ v c r cof little use for
surgical guidance clue to the neural variatioiis ancl lack of
anatomic relatioilships iii the ccrvical rcyjori of tlic clog. Two
composite drawings were rnadr froiii our dissections to tlcrrioustrate the cervical aiiatorriy of the caiiiiie cardiac nerves
(figs. 1 aiid 2 ) . The vagosyrripatlictic relations are derrioiistrated from the base of the skull t o tlie arch of tlic aorta in
Fig. 2 Drawing of the relationships and constituent nerve fibers of the superficial and deep
cardiac plexuses of the dog.
0 Loft cardiovagal nerves.
0 1)cep cardiac plexus.
Superficial cardiac plrsui.
Esophageal branches of lcft rorurrent norvo.
+
+
,
80
LONG, T K U K X , PL:IEL)MAW N, O L W N 9 X D 1'HILLII'S
figure 1. Belationships of the autoilorriic nerves entering into
the formation of tlic superficial arid tleep cardiac plexuses arc
illustrated in figure 2. I t should be noted that most of the
cervical sympathetic trunk is located within the epineuriuni
of the vagus nerve (fig. 1). Also note that all cardiac iiervcs
arise from the vagus nerves and sympathetic trunks low i l l
the iicck, adjacent to the first rib.
One can see the usual arrangement of the cardiac branches
a s they arise from the caudal ceivical ganglia a i d recurrelit
laryngeal nerves (fig. 2). The intimate anastomoses of vagal
and sympathetic cardiac nerve fibers within the caudal eel-vical ganglion are also dcmoiistrated by figures 1 and 2.
EXPERIMENT 1
Basal heart rate was secured in all GO clogs, and f i g u ~ c3 is
based on 300 individual ~ U K of
~ Sthese auinials. The average
heart rate at the beginning of the experiment was 86 beats per
minute, arid 66 beats per minute after 120 minutes. The slowest and fastest heart rates recorded a t each 30 minute interval
0
arc also shown in figure 9A. At the termination of Each run,
~ v l i c uthe thermometer was inserted and the animal stimulated,
the average heart rate increased to 97 beats per minute. A fall
in rectal terriperaturc accornpanicd the above electrocardiographic changes. Thcl average rectal temperature decreased
from 102.3"F at the start of the expcrimcnts to 100.8"F a t
their termination.
We observed no correlations lietween heart rate, l ~ o d y
weight or body size. Also, no correlation was observed between the heart rates of several dogs within a dominant breed
(e.g., fox hounds). However, a comparison of the 18 females
with the 42 male dogs rcvoalcd that the females tiad a significantly greater heart rate at each of tlic recorded intervals
(fig. 3B).
The essential changes noted in our serial electrocardiograms under basal conditions were increases in amplitude of
the Q, R and S waves. We also observed an increase in the
P-R and Q-T intervals. Of f a r greater interest was the appear-
81
CARDIAC DENERVATION
HEART RATE OF SIXTY NORMAL DOGS
I80
170
I60
I50
- AVERAGE
RATE
RATE
SLOWEST RATE
---- FASTEST
-.-.-
I
I
140
130
2
120
zz
I10
30
I
I
60
90
I
I20
TIME IN MINUTES
Fig. 3A Graph of the heart rate of 60 normal dogs. Note the decrease in the
average heart rate from the active state to a basal state (i.e., 86 to 66 beats per
minut,e). The fastest and slowest rates are also indicated.
Number
and sex
Start
of
experiment
30
min.
60
min.
90
min.
120
min.
Stimulation
18 Females
89
77
75
76
74
I09
4 2 Males
86
72
68
64
62
93
52
LONG, TRUEX, FRIED,XANN,
OMEN AND PHILLIPS
ance of phasic sinus arrythmia that accompanied the resting,
or basal heart rate. Such arrythmia increased in frequency
with each serial tracing and was almost always present at the
90 and 120 minute intervals. The phasic sinus arrythmia was
observed when the R-R interval was longest, namely, during
expiration. Other electrocardiograph abnormalities encountered under basal conditions included blocked ectopic atrial
and ventricular beats, atrioventricular block and nodal escape
beats.
EXPBKIMEST 2
Electrocardiographic studies were performed on the second
and fifth postoperative days for a period of 30 days. Subsequent records were then taken at less frequent intervals
for as long as 60 days. We observed no significant changes in
the heart rate followiiig bilateral sympathectomy. As noted in
figure 4,the heart rate after sympathectomy increased slightly
(i.e., 8.674) after 90 minutes had elapsed. However, the
animal’s cardiac response to stimulation remained unaltered
(fig. 4).
HEART RATE 6% 19 SYMPATHECTOMIZEO DOGS
w
-PREOPERATIVE
‘gI-
(CONTROL) RATE
POSTOPERATIVE RATE
z
a
K E 80
70
CL
W
m
50
30
60
TIME IN MINUTES
90
120
Fig. 4 Graph of the heart rate of 1 9 dogs before and after bilateral sympathectomy.
EXPERIMENT 3
The effect of bilateral cervical vagectomy upon the heart
rate of the dog is shown in figure 5. Three striking results can
be noted in this data. First, the average postoperative heart
rate is almost double the preoperative rate of the same animals
83
CARDIAC DENERVATION
due to the absence of vagal inhibition on the heart. Secondly,
there is very little fluctuation in the heart rate at each of the
recorded intervals over a period of 130 minutes.
HEART RATE OF 15 VAGECTOMIZED DOGS
160I3
z
c
150-
--- POSTOPERAT IV E RATE
--.-- - -- - --- ----- _ _ _ _ - - -___---
-
--/-
140U
130-
g
a
g
120110-
z
2
5 loo-
I-
501
1
I
I
I
30
60
90
I20
TIME I N MINUTES
Fig. 5 Graph of the heart r a t e of 15 animals before and a f t e r bilateral
vagectomy. After vagw resection, note the increased heart rate (150 beats per
minute) and loss of cardioaeceleration upon stimulation.
Electrocardiographic tracings of such animals shorn a very
characteristic uniformity of the R-R intervals with no evidence of phasic sinus arrythmia. The third important feature
shown in figure 5 is the minimal amount of cardiac acceleration
that results from stimulation even though such animals still
had their sympathetic nerve fibers intact.
Several bilaterallygva ectomized dogs were observed postoperatively for periods longer than 6 days. I f such animals
are sustained by good nutritional care and kept free from postoperative infection, the heart rate did become slower than the
rate shown in figure 5. This decrease in heart rate was most
84
LONG, TRUEX, FRIEDMANN, OLSEN AND PHILLIPS
obvious in animals that survived from 10 to 15 days. The
slowest heart rate observed in our animals after bilateral
vagectomy was 80 beats per minute.
EXPERIMENT 4
This series of 9 animals, subjected to complete denervation,
demonstrated heart rates that paralleled the results shown
in experiment 2 and experiment 3. Data from these animals
are shown graphically in figure 6. It will be noted that after
sympathectomy these animals still possessed accelerator nerve
fibers to the heart, and that the heart rate could be accelerated
even more by somatic stimulation (fig. 6).
HEART RATE OF 9 SYMPATHECTOMIZEO
AND VAGECTOMIZEO DOGS
- PREOPERATIVE (CONTROL) RATE
--- POST SYMPATHECTOMY RATE
50I
I
I
I
60
70
I20
TIME IN MINUTES
Fig. 6 Graph of the heart r a t e of 9 dogs a f t e r bilateral sympatheetomy and
vageetomy. Note t h a t the postoperative rate a f t e r sympathectomy and vagectomy
approximates 110 beats per minute. Compare to postoperative vageetomy rate in
figure 5.
30
When these animals were later subjected to bilateral
vagectomy, the heart rate became faster and devoid of ffuctuations. It should be noted that although the heart rate increased
following bilateral vagectomy (110 beats per minute in fig. 6),
these sympathectomized and vagectomized animals did not
CARDIAC DENERVATION
85
demonstrate as fast a heart rate as those having only a bilateral vagectomy (150 beats per minute in fig. 5). Again it can
be seen, that after complete denervation, the animals lost their
ability to respond to somatic and emotional stimulation.
Animals that survived for longer periods did demonstrate a
slight decrease in heart rate from that shown in figure 6. The
only times we observed even a slight increase in heart rate
following complete denervation was in moribund animals.
I n such cases we also observed abnormal features in the
electrocardiographic records.
DISCUSSION
The uniforim electrocardiographic method used in the present investigation eliminated the individual error of counting
the animal's pulse to determine the basal heart rate. We
believe the use of special tables, lack of animal training and
elimination of anesthesia are also advantages inherent in this
study. Such precautions probably account for the basal heart
rate of 66 beats per minute observed by the present authors.
It should be recalled that Gasser and Meek ('14) reported an
average rate of 109 beats per minute; Samaan ( '34a,b) 90
beats; and Murphy ( '42) 50-56 beats per minute. The slow
heart rate reported by Murphy was further influenced by his
selection of only the slowest rate for each animal.
The 121 beats per minute reported by Horwitz, Spanier and
TViggers ( ' 5 3 ) represented their observations on resting dogs
alone. They made no evaluations after prolonged animal rest,
or conditions that simulated our basal timed intervals. However, our measurement of the individual elements of the canine
electrocardiograim was very similar to their reported results.
The above experimental results are in agreement with those
of other investigators who have observed that some of the
acceleration of the heart with exercise is mediated through
the fibers of the vagus nerve (Jourdan and Nowak, '36;
Brouha, Cannon and Dill, '36; Brouha and Nowak, '39;
Brouha, Nowak and Dill, '39). The present study also corroborates the conclusions of others, that after sympathectomy,
86
LONG, TRUEX, FRIEDMANN, OLSEN AND PHILLIPS
the heart of a n animal behaves essentially the same as that
of a normal intact one (Samaan, '34a,b ; Murphy, '42 ; Essex
et al., '43a,b).
These experiments showed that the heart rate after
vagectomy alone was more rapid than the rate after spmpatlicctomy and vagectomy. This implies a continuous cardiac
accelerator tone as a manifestation of sympathetic activity,
and supports the findings of Bronk et al. ('36). Following
sympathectomy alone, the tonic accelerator activity of the
cardiovagal nerves was undoubtedly of sufficient magnitude
to compensate for the absence of sympatlietic accelerator tone
(fig. 4).
The total denervation experiments reported above are
worthy of additional comment, for all extrinsic elements of the
autonomic iiervous system were separated from the heart. I n
such animals, only the intrinsic ganglion cells with their axons
and sensory fibers of the dorsal root ganglion, remained
within the heart. W e had previously re'moved the dorsal root
ganglia of the eighth cetvical to the eighth thoracic spinal
nerves in 4 dogs. The trophic skin lesions following such sensory deii~n7ationarc' cxtcnsive and would require additional
nursing care. F o r this reason the dorsal roots were left intact
in the present study. Thus when all accelerator and inhibitory
nerve fibers were elirnirtatctl from the heart of adult dogs, the
heart maintained an intrinsic rate that approximated 110 beats
per minute (fig. 6). This rate for the denervated dog heart
might therefore be looked upon as the intrinsic myogcnic rate.
Such a heart rate must be initiated and maintained by the
modified muscular tissues of the intrinsic cardiac conduction
systern.
The role of the chromaffin tissue in cardiac acceleration
remains unanswered as of the present date. It should be
recalled that such tissue has been observed in the atrial wall
of the heart itself (Truex, '50). However, Brouha, Cannon
and Dill ( '36) concluded that cardiac acceleration with excitement and excercise was not due to adrenalin secretion, sym-
CARDIAC DENERVATION
87
pathin or increased sympathetic tone. The effect of various
drugs upon the denervated heart merits continued investigation.
CONCLUSIONS
1. The extrinsic autonomic nerve fibers to the heart were
dissected. The pertinent anatomy is illustrated in the present
study as a guide for selective surgical denervation procedures
in this animal.
2. The basal heart rate of 60 normal adult dogs was determined with electrocardiographic equipment and a uniform
procedure. The average heart rate decreased from an average
of 86 beats at the start of 300 separate experiments to 66 beats
per minute after 120 minutes of quiet rest. Stimulation at the
end of the experiments caused an increase in average cardiac
rate to 97 beats per minute. Rectal temperature decreased
from 102.3"F to 100.8"F during the two hour period of rest.
The heart rate of female dogs exceeded that of male dogs.
3. The heart rate and nlectrocardiogram of 19 dogs showed
t
no chronic changes following bilateral sympathectomy. Cardiac acceleration persisted after such nerves were removed
surgically.
4. The heart rate of 15 dogs increased to approximately
150 beats per minute after high bilateral cervical vagectomy.
The heart rate did not increase significantly with stimulation
even though the sympathetic nerve fibers were intact. The
resulting electrocardiograms presented a uniform and characteristic appearance.
5. After surgical resection of all sympathetic and vagal
cardiac fibers, the heart rate increased to approximately 110
beats per minute. Nine animals in this series of experiments
demonstrated lack of cardiac acccleration upon stimulation,
and an electrocardiogram similar to that of vagectomized
animals. It is presumed that the heart beat and rate in such
animals is initiated and maintained by the intrinsic conduction
system of the heart itself.
58
LONG, TRUEX, FRIEDMANN, OMEN A N D PHILLIPS
6. The significance of such vagal cardioaccelerator fibers is
presented and the pertinent electrocardiographic results are
discussed.
ACKNOWLEDGMENTS
The authors express their sincere appreciation to Josephine
Bishof, Marjorie Stodgell, Irene Gamerman, Paul Moock,
Edward Hoffman and Dr. Walter Maloney f o r their research
and technical assistance.
L I T E R A T U R E CITED
BROXR,D. W., I,. K. FERGUSON,
R. MARGARIA
AND D. U. LOLAND1936 The
activity of the cardiac sympathetic centers. Am. J. Physiol., 117:
237-249.
B ~ o r ~ L.,
4 , W, B. CANNONAND D. B. DILL 1936 The heart rate of the Sym
pathectomized dog in rest and excerrise. 3. Physiol., 87: 345-359.
E R O U H I,.,
~ , AND S. J. G, NOWAK 1939 The role of the vagus in the cardioaccelerator action of atropine in s~'rnpat1~1xtomizeddogs. J. Pl~ys~ol.,
95: 439-453.
BROUH
1, L., S.J. G. N o w a ~A N D D. B. DILL 1939 The role of t h e vagus 111 the
cardioaccclerator action of muscular exercise and emotion in synipatheetomized dogs. J. Physiol., 95 I 454-463.
ESSEX,
If. E.,J F. HEXRICK, F t 2 . MANNAND E. J. BALDZS 19438 The eff'ect
of atropine on the coronary blood flow of trained dogs with denervated
and partially denervated hearts. Am. J. Physiol., 238: 683-686.
ESSEX,H, E., J. F. HERRICK,
E. J. BALDES
A N D F. C. M ~ N N1943b Effccts of
exercise on the eoronary blood flow, heart rate and blood pressure of
trained dogs with denervated and partially dcnervated hearts. Am J.
Phj siol., 138: 687-697.
FOUELIX, C. 1851 De causa mortis post ncrvos vagos dissectos instantis. J . C.
Schunmanni e t C. Mathieseni, Dorpat. 1-38.
GASSER, €I. S.,AND J . W. MEEK 1914 A study of the mechanism b y which
muscu1,zr exercise pioduces acceleration of the heart. Am. J. Physiol ,
5 4: 48-71.
1 3 0 ~ ~ 1 S.
~ 2A.,
, M. E. SPANIER
AND H. C. X'IGGCRS
1953 T!le electrocardiogram
of the normal dog. Proc. SOC.Exp. Biol. and Men., 84: 721-125.
H I J N T , R., A N D D. w. I T A R R I N G T O N 1897 Note on the phvsiology of the czrdiac
nerves of the calf. J. Exp. Med., 3 : 723-127.
JOURDAN,
F., AND S. J. G. NOWAK1934 Les fibres cardio-accelPratrices dans le
nerf pneumogastriquc du chien; leur origine e t leur trajel. C. R. Soc
Biol., Paris, 2 1 7 : 234-238.
1936 Etude experimentale ehez lo chien des fibres cardio-aeceleratrices du vague. Arch. Internat. de Pharmacodyn. et d e Therap., 53:
121-135.
KABAT,€1. 1940 The cardioaccelerator fibers of the vagus nerve of the dog.
Am. J. Physiol., 128: 246-257.
89
CARDIAC DENERVATION
MURPHY,Q. 1942 The influence of the accelerator nerves on the basal heart
rate of the dog. Am. J. Physiol., 137: 727-730.
1951 The cardioaccelerator
OKINAKA,S., K. NAKAO,
>
IKEDO
I. AND K. SHIZUME
fibers in the vagus nerve. Tohoku J. of Exper. Med., 54: 393-398.
SANAAN,
A. 1934a Muscular work in dogs submitted to different conditions of
cardiac and splanchnic innervations. J. Physiol., 83 : 313-331.
1934b The antagonistic cardiac nerves and heart rate. J. Physiol.,
83: 332-340.
SCHIFF,M. 1849 Experimentelle untersuchungen iiber die nerven des herzens.
Areh. Pliysiol., Reilk, Br 166-234.
TRUEX,R. C. 1950 Chromaffin tissue of the sympathetic ganglia and heart.
Anat. Rec., 108: 687-697.
TRUEX,R. C., J. C. SCOTT,
D. M. LONG
AND M. Q. SXYTHE 1955 Effect of vagus
nerves on heart rate of young dogs: An anatomic-physiologic study.
Anat. Rec., 123: 201-226.
WEBER,E., AND E. H. WEBER 1845 Experimenta, quibus probatus nervos vagos
rotatione machinae galvano-magneticae initatos, motum cordis retardare e t adeo intercipere. Annali Universali d i medicina, 216 227-228.
.’
Документ
Категория
Без категории
Просмотров
4
Размер файла
891 Кб
Теги
following, autonomic, rate, heart, dog, denervation
1/--страниц
Пожаловаться на содержимое документа