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.     

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

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.     

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.     

High altitude influence on the level and turn-over time of cardiac norepinephrine in rats

Summary In rats exposed to an altitude, of 2,900 meters the level of endogenous cardiac norepinephrine decreases after the 5th day of exposure. The turner-over time of the amine proceeds in 3 steps which are probablyrelated to periods of stress and adaptation: initial increase, important decrease from the 5th day and return to a normal value from the 12 th day.     

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.     

The effect of verapamil and dibutyrul cAMP on the spontaneous activity of the sinus node

Summary Verapamil stops the electrical activity of the sinus node cells. In the presence of verapamil, dibutyryl cAMP brings about a recovery of the spontaneous activity, whereas noradrenaline is ineffective.     

The effect of combined chronic hypoxia and N-ethyl-N-nitrosourea on the carotid bodies of rats

Summary We measured the carotid body volume of rats treated with chronic hypoxia alone and chronic hypoxia together with a single neonatal injection of N-ethyl-N-nitrosourea (10 mg/kg). All the animals so treated showed enlargement of their carotid bodies, but no carotid body chemodectomas occurred.This work was supported by a grant from the North West Cancer Research Fund.     

The effect of combined chronic hypoxia and N-ethyl-N-nitrosourea on the carotid bodies of rats.

We measured the carotid body volume of rats treated with chronic hypoxia alone and chronic hypoxia together with a single neonatal injection of N-ethyl-N-nitrosourea (10 mg/kg). All the animals so treated showed enlargement of their carotid bodies, but no carotid body chemodectomas occurred.     

The antagonism of potassium and catecholamines on the vascular tone of isolated arterial segments

Zusammenfassung An isolierten Segmenten der Art. facialis (Rind) wurde der Innendruck (Anfangsdruck 100 mm Hg) fortlaufend isometrisch registriert, während die Aussenseite von Tyrode-Lösungen mit verschiedenem Kalium- und Catecholamingehalt umspült wurde. Die durch die Catecholamine (5 × 10 bis⁷–5 × 10^–6g/ml) induzierte Vasokonstriktion kann durch geringe Erhöhung der Kaliumkonzentration (von 2,8 auf 6,34 bis ca. 10 mmol) unterdrückt werden. Bei gleichzeitiger Applikation beider Substanzen setzt sich die dilatatorische Wirkung der K⁺-lonen durch.     

The influence of cocaine and reserpine on the effect of several sympathomimetic amines on the mouse iris

Zusammenfassung Der direkte, indirekte und gemischte Wirkungsmodus von fünfzehn sympathomimetischen Aminen an der Mäuseiris wurde an cocainisierten und reserpinisierten Tieren bestimmt, wobei sich gewisse Unterschiede gegenüber dem Wirkungsmodus an der Katzennickhaut zeigten.     

The influence of furosemide on the renal excretion of chloramphenicol and its metabolites.

Simultaneous administration of chloramphenicol and furosemide (10 mg i.v.) decreased urinary excretion of chloramphenicol but increased the excretion of its metabolites as aryl amines and total nitro compounds. These latter increases were directly related to Na excretion.     

The influence of oestrogen and thyroid on the pituitary and blood content of FSH and LH

Résumé L'effet de l'administration du «Benzoate d'stradiol» et des hormones thyroïdales seuls ou en combinaison sur le FSH et LH contenus dans le sang et les hypophyses des femelles rats castrés a été étudié. Il a été trouvé que l'stradiol et l'extract de la thyroïde quand ils sont administrés seuls produisent une baisse, dans le sang, du FSH et une hausse du LH. L'administration combinée de ces deux hormones renforce cet effet.