scholarly journals EFFECT OF PROSTAGLANDINS E1 AND F2α ON HEART RATE BY DIRECT INJECTION INTO THE CANINE SINUS NODE ARTERY

1972 ◽  
Vol 22 (5) ◽  
pp. 734-736 ◽  
Author(s):  
Shigetoshi CHIBA ◽  
Tamio NAKAJIMA ◽  
Jiro NAKANO
Keyword(s):  
Heart Rate ◽  
Sinus Node ◽  
Direct Injection ◽  
Sinus Node Artery

Sinus bradycardia during injections directly into the sinus node artery

1963 ◽  
Vol 204 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Thomas N. James ◽  
Reginald A. Nadeau
Keyword(s):  
Heart Rate ◽  
Sinus Bradycardia ◽  
Sinus Node ◽  
Normal Heart ◽  
Anatomic Structure ◽  
Ionic Content ◽  
Sinus Node Artery ◽  
Nutrient Artery ◽  
Normal Heart Rate ◽  
Cervical Vagotomy

In over 90% of 800 experiments in 75 dogs injection directly into the sinus node artery produced sinus bradycardia. Studies to explain this phenomenon included control of temperature, pH, osmolarity, oxygen, and ionic content of injecting solutions. Although unphysiologic variations of any of these are known to produce marked alterations in the sinus mechanism, sinus bradycardia from injection still occurred when they were controlled. Neurogenic mechanisms were excluded by bilateral cervical vagotomy, and by direct perfusion of the sinus node with atropine, hexamethonium, and trimethaphan. Because of the unique anatomic structure of the sinus node, which completely surrounds its nutrient artery, it is suggested that the sinus bradycardia may simply be the consequence of distending the sinus node artery. Implications concerning autoregulation of the normal heart rate are discussed.

Effect of vasoactive intestinal peptide on pacemaker location and heart rate in the dog atrium

1998 ◽  
Vol 76 (4) ◽  
pp. 457-462 ◽  
Author(s):  
Arnold Pintér ◽  
Réginald Nadeau ◽  
Nazih Dandan ◽  
Pierre L Pagé
Keyword(s):  
Heart Rate ◽  
Vasoactive Intestinal Peptide ◽  
Sinus Node ◽  
Sinus Node Artery ◽  
Anesthetized Dogs ◽  
Similar Decrease ◽  
Intravenous Sodium ◽  
Unipolar Electrograms ◽  
Positive Chronotropic Effect ◽  
Atrial Mapping

Vasoactive intestinal polypeptide (VIP) was either injectedintravenously (300 pmol·kg–1) or perfused (1 nmol in 1 min) into the sinusnode artery (SNA) in anesthetized dogs to study its effect on subsidiary atrial pacemakers.Isochronal maps were obtained from 128 unipolar electrograms recorded on the epicardialsurface of both atria in nine animals. When VIP was perfused into the SNA or injectedintravenously, heart rate increased by 29 ± 16% and 12 ± 12%, and blood pressure decreased by16 ± 15 mmHg (1 mmHg = 133.3 Pa) and 24 ± 18 mmHg, respectively. Nosignificant change in heart rate (3 ± 6% decrease) accompanied a similar decrease in bloodpressure after an intravenous sodium nitroprusside perfusion. The perfusion of VIP into the SNAas well as the intravenous injection of VIP induced a shift of the pacemaker site to the region ofBachmann’s bundle in a third of the preparations, while the pacemaker remained in the sinusnode area in two thirds. A perfusion of isoproterenol into the SNA produced a similar heart rateincrease (32 ± 14%, NS vs. VIP), and shifted the pacemaker site rostrally within the sinus node inthree of five preparations, or to the region of Bachmann’s bundle in two of five preparations.The response to VIP in the location of the pacemaker was significantly different from theresponse to isoproterenol. Repeated perfusions of VIP into the SNA after 10-, 25-, 40-, and60-min intervals produced 2 ± 13% (p < 0.005 vs. the effect of first VIP administration),14 ± 12% (p < 0.05), 10 ± 12% (p < 0.05) and 30 ± 13% (NS) heart rateincreases, respectively, thereby demonstrating a tachyphylactic effect. In conclusion, VIP seemsto exert its positive chronotropic effect directly (probably via specific VIP receptors), althoughthe phenomenon of tachyphylaxis may suggest an indirect sympathomimetic mechanism.Key words: vasoactive intestinal peptide,subsidiary atrial pacemakers, sinus node artery, atrial mapping.

Acute effects of amiodarone in the isolated dog heart

1983 ◽  
Vol 61 (4) ◽  
pp. 308-314 ◽  
Author(s):  
Miyoharu Kobayashi ◽  
Diane Godin ◽  
Réginald Nadeau
Keyword(s):  
Sinus Node ◽  
Direct Injection ◽  
Left Ventricular ◽  
Ventricular Muscle ◽  
Inotropic Effects ◽  
Percent Change ◽  
Sinus Node Artery ◽  
Arterial Blood ◽  
Chronotropic Effects ◽  
Dose Dependent

Direct injection of amiodarone (10–1000 μg) into the sinus node artery of the isolated blood-perfused dog atrium produced dose-dependent negative inotropic and chronotropic responses that were unaffected by atropine. Intraarterial amiodarone also had a negative inotropic action on isolated left ventricular muscle preparations electrically paced at 1.5 to 2.0 Hz. A continuous infusion of 100 μg/min of amiodarone significantly suppressed the positive chronotropic effect of norepinephrine whether expressed in percent change or in absolute values; its positive inotropic effect expressed in percent change was not suppressed but rather enhanced by amiodarone. Calcium chloride induced positive chronotropic and inotropic effects expressed in percent change were, respectively, slightly suppressed and enhanced by amiodarone. Intravenous injection of amiodarone (5 mg/kg) decreased the heart rate and blood pressure of the support dog and produced a negative inotropic response in the isolated left ventricular muscle preparation perfused with arterial blood from the support dog. These results suggest first, that amiodarone has direct negative inotropic and chronotropic effects that are not mediated by cholinergic mechanisms and second, that it has a depressive action on norepinephrine and calcium-induced positive chronotropic effects and an enhancing action on their positive inotropic effects.

Direct effects in vivo of angiotensins I and II on the canine sinus node

1991 ◽  
Vol 69 (3) ◽  
pp. 389-392 ◽  
Author(s):  
C. Lambert ◽  
D. Godin ◽  
P. Fortier ◽  
R. Nadeau
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Angiotensin Ii ◽  
Sinus Node ◽  
Converting Enzyme ◽  
Chronotropic Effect ◽  
Angiotensin I ◽  
Sinus Node Artery ◽  
Blood Pressures

The chronotropic responses to angiotensins I and II (5 μg in 1 mL Tyrode's solution) injected into the sinus node artery were assessed before and after the intravenous administration of captopril (2 mg/kg) and saralasin (20 μg/kg) in anaesthetized dogs. The effects of angiotensin II given intravenously were also observed. The animals (n = 8) were vagotomized and pretreated with propranolol (1 mg/kg, i.v.) to prevent baroreceptor-mediated responses to increases in blood pressure. Injection of angiotensin I into the sinus node artery induced significant increases in heart rate (114 ± 6 vs. 133 ± 6 beats/min) and in systemic systolic (134 ± 13 vs. 157 ± 14 mmHg; 1 mmHg = 133.3 Pa) and diastolic (95 ± 10 vs. 126 ± 13 mmHg) blood pressures. Similar results were obtained when angiotensin II was injected into the sinus node artery, but intravenous injection induced changes in systolic (138 ± 8 vs. 180 ± 25 mmHg) and diastolic (103 ± 8 vs. 145 ± 20 mmHg) blood pressures only. Captopril induced a significant decrease in systolic (118 ± 11 vs. 88 ± 12 mmHg) and diastolic (84 ± 9 vs. 59 ± 9 mmHg) blood pressures without affecting the heart rate (109 ± 6 vs. 106 ± 6 beats/min). Saralasin produced a significant increase in systolic (109 ± 7 vs. 126 ± 12 mmHg) blood pressure only. Increments in heart rate and systolic and diastolic blood pressures in response to angiotensins I and II were, respectively, abolished by captopril and saralasin. It was concluded that angiotensin II has, in vivo, a direct positive chronotropic effect that can be blocked by saralasin. The antagonism by captopril of the response to angiotensin I suggests the presence of local tissue converting enzyme activity in the region of the sinus node.Key words: angiotensin, chronotropic effect, tissue converting enzyme.

Effects of neuropeptides on heart rate in dogs: comparison of VIP, PHI, NPY, CGRP, and NT

1988 ◽  
Vol 255 (2) ◽  
pp. H311-H317 ◽  
Author(s):  
D. F. Rigel
Keyword(s):  
Heart Rate ◽  
Neuropeptide Y ◽  
Vasoactive Intestinal Polypeptide ◽  
Sinus Node ◽  
Calcitonin Gene Related Peptide ◽  
Adrenergic Blockade ◽  
Related Peptide ◽  
Sinus Node Artery ◽  
Calcitonin Gene ◽  
Intestinal Polypeptide

This study was designed to evaluate the potential chronotropic actions of several cardiac neuropeptides in pentobarbital-anesthetized dogs. After bilateral vagotomy and stellectomy and muscarinic receptor blockade, I injected vasoactive intestinal polypeptide, peptide histidine isoleucine, neuropeptide Y, neurotensin, and calcitonin gene-related peptide into the intact sinus node artery. Neurotensin, calcitonin gene-related peptide, and neuropeptide Y exhibited no physiologically significant changes in heart rate. However, the structural homologues vasoactive intestinal polypeptide and peptide histidine isoleucine each augmented heart rate with maximal increases (approximately 120 beats/min) similar to those of norepinephrine. Vasoactive intestinal polypeptide and peptide histidine isoleucine were twice and 1/18, respectively, as potent as norepinephrine. The cardioacceleratory responses to vasoactive intestinal polypeptide and peptide histidine isoleucine were more slowly developing and longer lasting than those of norepinephrine. The responses to these two peptides were unchanged after beta-adrenergic blockade with propranolol in a dose sufficient to eliminate or greatly attenuate the norepinephrine tachycardia. These results indicate a potential role of endogenous vasoactive intestinal polypeptide and peptide histidine isoleucine in nonadrenergic, noncholinergic heart rate control in the dog.

Abnormalities in baroreflex control of heart rate in canine heart failure

1981 ◽  
Vol 240 (5) ◽  
pp. H793-H799 ◽  
Author(s):  
C. W. White
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Hypertonic Saline ◽  
Carotid Sinus ◽  
Sinus Node ◽  
Right Heart Failure ◽  
Canine Heart ◽  
Baroreflex Control ◽  
Chronotropic Response ◽  
Sinus Node Artery

The mechanism of the attenuated arterial baroreceptor control of heart rate in heart failure was studied in 18 unanesthetized dogs after the development of chronic right-heart failure and compared to 12 control animals. The change in heart rate and arterial pressure in response to increases in right carotid sinus pressure during isolated carotid sinus perfusion was markedly reduced in heart failure (P less than 0.05). After vagotomy the difference in heart rate responses persisted, but was less pronounced (P = 0.065). The chronotropic response to perfusion of the sinus node artery with acetylcholine in heart-failure dogs showed a selectively depressed response, when compared to norepinephrine and hypertonic saline. The ratio of the change in heart rate in heart-failure vs. control dogs was 57% for acetylcholine but was not diminished for hypertonic saline (114%). The effect of direct vagal nerve stimulation on changes in heart rate was also markedly reduced in heart-failure dogs. These studies demonstrate that the alterations in baroreceptor control of heart rate in heart failure involve both the parasympathetic and sympathetic baroreflex efferent limbs. There is, in addition, a depressed responsiveness of the sinus node to cholinergic stimuli.

scholarly journals RNAseq shows an all-pervasive day-night rhythm in the transcriptome of the pacemaker of the heart

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yanwen Wang ◽  
Cali Anderson ◽  
Halina Dobrzynski ◽  
George Hart ◽  
Alicia D’Souza ◽  
...  
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Circadian Clock ◽  
Sick Sinus Syndrome ◽  
Sinus Node ◽  
Signalling Pathways ◽  
Resting Heart Rate ◽  
Ion Channel Regulation ◽  
Channel Regulation ◽  
Physiological Systems

AbstractPhysiological systems vary in a day-night manner anticipating increased demand at a particular time. Heart is no exception. Cardiac output is primarily determined by heart rate and unsurprisingly this varies in a day-night manner and is higher during the day in the human (anticipating increased day-time demand). Although this is attributed to a day-night rhythm in post-translational ion channel regulation in the heart’s pacemaker, the sinus node, by the autonomic nervous system, we investigated whether there is a day-night rhythm in transcription. RNAseq revealed that ~ 44% of the sinus node transcriptome (7134 of 16,387 transcripts) has a significant day-night rhythm. The data revealed the oscillating components of an intrinsic circadian clock. Presumably this clock (or perhaps the master circadian clock in the suprachiasmatic nucleus) is responsible for the rhythm observed in the transcriptional machinery, which in turn is responsible for the rhythm observed in the transcriptome. For example, there is a rhythm in transcripts responsible for the two principal pacemaker mechanisms (membrane and Ca2+ clocks), transcripts responsible for receptors and signalling pathways known to control pacemaking, transcripts from genes identified by GWAS as determinants of resting heart rate, and transcripts from genes responsible for familial and acquired sick sinus syndrome.

Evaluation of β-Adrenerglc Blocking Agents in Presence of Adrenergic Tone

1972 ◽  
Vol 50 (5) ◽  
pp. 381-388
Author(s):  
Victor Elharrar ◽  
Reginald A. Nadeau
Keyword(s):  
Dose Response ◽  
Sinus Node ◽  
Stellate Ganglion ◽  
Sodium Pentobarbital ◽  
Response Curves ◽  
Chronotropic Response ◽  
Blocking Agents ◽  
Sinus Node Artery ◽  
Anesthetized Dogs ◽  
The Right

The importance of the level of adrenergic tone in the determination of the dose–response curve to noradrenaline (NA) and in the evaluation of β-adrenergic blocking agents was studied in open-chest sodium pentobarbital anesthetized dogs by injecting drugs directly into the sinus node artery. Changes in the level of adrenergic tone by stimulating the right stellate ganglion resulted in variation of the observed chronotropic response to NA and of its ED50. The chronotropic responses were corrected by taking into account the underlying adrenergic tone. The negative chronotropic effect of dl-propranolol (1 and 10 μg) appeared to be related to its β-blocking properties and not to its quinidine-like effects as shown by the lack of effect of d-propranolol injected at the same doses. The magnitude of the negative chronotropic effects of 10 μg of propranolol and 100 μg of practolol, oxprenolol, and sotalol was shown to be related to the initial heart rate and consequently to the level of adrenergic tone. The comparison of these four β-blocking agents was carried out on corrected dose-response curves to NA. Their relative potencies were found to be: propranolol > oxprenolol > practolol > sotalol, corresponding to ratios of 1, [Formula: see text], [Formula: see text], and [Formula: see text]

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