Effects of carotid sinus nerve stimulation on respiratory sinus arrhythmia and respiratory blood pressure waves of the dog

Summary The effect on the amplitudes of RSA and RBPW of the time of the stimulus in the cardiac cycle, and also of continuous stimulation were studied. When the stimulus train was applied near peak systole the amplitudes of RSA and RBPW decreased. Stimulation in late systole increased both RSA and RBPW. Continuous stimulation did not exert any effects on RSA and RBPW.     

Influence of cervical sympathetic nerve stimulation on carotid sinus baroreceptor afferents

Summary In rabbits and dogs, the response of low-threshold carotid sinus baroreceptor afferent fibres to cervical sympathetic nerve stimulation at various non-pulsatile steady pressures was examined. Fibres which possessed a rhythmic bursting discharge at low pressures increased this activity during sympathetic stimulation; all other low-threshold afferents were unaffected.This work was supported by the Medical Research Council of Canada and the British Columbia Heart Foundation.     

Influence of continuous and intermittent (R-wave triggered) electrical stimulation of the carotid sinus nerve on the static characteristic of the circulatory regulator

Zusammenfassung Bei narkotisierten Hunden wurde der Karotissinusnerv sowhl mit Dauerimpulsen als auch mit R-Zacken-gesteuerten Impulszügen elektrisch gereizt. Die Blutdruckcharakteristik zeigt, dass der Messbereich des Kreislaufreglers unter kontinuierlicher und ohne Reizung bei etwa gleichen Druckwerten liegt. Die Reizung mittels Impulszügen führt dagegen zu einer Verlagerung des Messbereiches zu niederen endosinualen Drücken.     

Action of N-butylnorsympathone on the effects of cardioaccelerator nerve stimulation in the dog]

In Dogs anaesthetized with pentobarbital (30 mg . kg-1), N-butylnorsympathone (20 mg . kg-1 i.v.) reduced the bradycardia induced by stimulating the cardiac nerve (1, 2, 5, 10 Hz). Phentolamine (1 mg . kg-1 i.v.) or yohimbine (0.3 mg . kg-1 i.v.), two potent alpha-adrenoceptor blocking agents known to block presynaptic alpha-adrenoceptor induced a recovery of the effect of cardiac nerve stimulation. Prazosine (0.050 mg . kg-1 i.v.) an alpha-adrenoceptor blocking agent known to be ineffective on presynaptic alpha-adrenoceptors did not induce a recovery. However neither phentolamine or yohimbine were able to prevent the effects of N-butylnorsympathone. Neither haloperidol (0.050 to 2 mg . kg-1 i.v.) or pimozide (0.20 to 1 mg . kg-1 i.v.) induced a recovery or prevented the effects of N-butylnorsympathone. These results suggest that N-butylnorsympathone may stimulate presynaptic receptors which do not resemble classical presynaptic alpha-adrenoceptors or dopamine receptors.     

Nitroglycerin on the carotid artery and femoral artery of the dog

Résumé In vitro, la nitroglycérine antagonise aisément la contraction de l'artère carotidienne du chien provoquée par la noradrénaline, ce qui n'est pas le cas pour l'artère fémorale. In vivo cependant les différences de comportement de ces deux artères envers la nitroglycérine ne semblent pas être liées à des propriétés intrinsèques des vaisseaux, mais bien à des reflexes sympathiques.     

Regional blood flow antagonism induced by central thermal stimulation in the conscious dog

Zusammenfassung Am wachen Hund wurde bei selektiver thermischer Reizung von Rückenmark und Hypothalamus ein regionaler Durchblutungsantagonismus für das kutane und intestinale Gefässgebiet als thermoregulatorische Antwort nachgewiesen.     

Effects of stimulation and inhibition of bicarbonate reabsorption on the renal tubular transport of sodium and chloride in the dog

Résumé L'acidose respiratoire aiguë n'affecte pas significativement la réabsorption tubulaire du Na et du Cl, alors que celle-ci est déprimée par l'administration d'acétazolamide.     

Effect of norepinephrine and vasopressin on carotid sinus baroreceptor activity in the anesthetized rabbit

Summary Norepinephrine (NE) 10^–6 M or vasopressin (VP) 12.5 U/ml were injected into the isolated carotid sinus of anesthetized rabbits. The sinus was exposed either to the arterial pressure or to a pressure controlled reservoir. Multifiber and single fiber recordings were made. Both NE and VP increased baroreceptor activity at all sinus pressures but decreased activity in a few fibers. The results are consistent with the drugs having their effects on smooth muscle fibers in the adventitia.Acknowledgments. This work was supported by grants from the Medical Research Council of Canada and the B.C. Heart Foundation. The authors are grateful to J. Sharp and D. Morton for their excellent assistance.     

Humoral autoregulation of blood flow and blood pressure

Zusammenfassung Vasoaktive Substanzen im arteriellen Blut können charakteristische Reaktionen des lokalen Strömungswiderstandes hervorrufen. Die einfachsten Beispiele dieser humoralen Autoregulation können durch intraarterielle Infusion von Acetylcholin (Autoregulation der Strömung) oder Noradrenalin (Autoregulation des Drucks) demonstriert werden. Es wird angenommen, dass der humoralen Autoregulation Bedeutung bei der normalen und pathologischen Kreislaufregulation zukommt.

---

---

Supported by NIH grant No. HE 11747.

---

The experiments were performed in the Division of Biomedical Engineering, University of Virginia, Charlottesville, USA.     

Effects of palytoxin on the electrical activity of dog and rabbit heart

Summary Reversible effects of palytoxin, extracted from colonies of the soft coralPalythoa caribaeorum, are described. There is a decrease of both membrane resting potential and overshoot during activity. Rise time of the action potential is prolonged, while repolarization is shortened. The electrical events resemble those seen with metabolic poisons.This work was supported by grant 10897 from the National Heart and Lung Institute, Bethesda, Md., and by grant 3.758. 72 from the Swiss National Science Foundation.I wish to thank Dr W. C. De Mello for hospitality in his department, Dr T. Morales for allowing me to use his equipment, Dr. J. Santos Martínez for providing me with hearts of poisoned and unpoisoned dogs, and Drs E. Toro-Goyco and A. M. Preston of the Department of Biochemistry for letting me have a sample of toxin.     

Reciprocal autoregulation of blood flow and blood pressure

Zusammenfassung Der Eingangswiderstand verschiedener Arterien wurde im Niederfrequenzbereich (0,0005 bis 0,25 Hz) mittels sinusförmig modulierter Pumpen-Perfusion mit arteriellem Blut an narkotisierten Hunden gemessen. Die Resultate lassen die Existenz zweier reziprok wirkender Autoregulationsmechanismen vermuten, deren Frequenzcharakteristik mit Hilfe eines einfachen linearen Modells simuliert werden konnte.

---

---

Supported by NIH Grant No. HE 11747.     

Influence of electrical stimulation on the subcellular distribution of dopamine-β-hydroxylase in the dog spleen

Résumé Une stimulation électrique in situ de la rate du chien provoque l'apparition de membranes contenant de la dopamine--hydroxylase. Les membranes sont très probablement le résultat d'une fusion de la membrane axonale et de la membrane vésiculaire, pendant le processus de décharge. Une telle formation de membranes indique que les particules chargées de noradrénaline ne peuvent être utilisées qu'une seule fois.     

Intracerebroventricular angiotensin II increases arterial blood pressure in rhesus monkeys by stimulation of pituitary hormones and the sympathetic nervous system

Summary Intracerebroventricular injections of angiotensin II in anesthetized rhesus monkeys increase systemic blood pressure and heart rate. These effects are accompanied by an increase in plasma ADH, cortisol, adrenaline and noradrenaline. Angiotensin II may participate in central mechanisms of blood pressure regulation by its stimulatory effect on the sympathetic nervous system, on ADH and on ACTH release in primates.