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Biomedical subjects

A Cevese

Publications and source records attributed to A Cevese.

46 records · Page 3Linked to original sources
PubMed1982

[Effects of Bitis gabonica venom on heart dynamics and circulatory resistance in the rabbit].

The effect on the cardiovascular system of intravenous injections of Bitis gabonica venom was studied on 10 urethan anesthetized rabbits, by giving the venom in three successive doses of .125 (I Dose), .250 (II Dose) and .500 (III Dose) mg/kg. In partial agreement with already reported data, the results of our experiments showed a powerful but transient fall of total peripheral resistance, which seemed to be relatively independent of doses. A cardiotoxic action leading to severe reduction of cardiac output was also found, but only at the II Dose; this effect was apparently irreversible, and was not enhanced by the III Dose. Moreover, a prompt bradicardic effect after each administration was found, which may not be attributed to direct effects of the venom on the cardiac pacemaker cells.

Animals↗
PubMed1981

Effects of combined stimulation of right and left vagus nerves on heart rate in rabbits.

The negative chronotropic effects of combined stimulations of the right and left vagus nerves were compared with the effects of single nerve stimulations in 10 urethan anesthetized rabbits. The combined stimulations gave smaller effects than single nerve stimulations at double frequency, over a wide range of frequencies: this was more evident for the right vagus compared with right plus left, rather than vice versa. It is concluded that the effects of combined stimulations are partially occluded and that the left vagus has smaller effects than the right vagus, although such difference becomes apparent only with combined stimulations. Possible mechanisms of occlusion are discussed.

Animals↗
PubMed1981

Interference of sympathetic innervation with reactive hyperemia in dog's skeletal muscle.

The reactive hyperaemia (RH) after 30 sec arterial occlusion was studied in normal and chromically sympathectomized dog hindlimbs, under general chloralose anaesthesia. RH reached higher peak flow in the sympathectomized limbs, but the percent increase of flow was the same in both hindlimbs. The time course of RH was reduced in normal limbs, thus leading to a 35% decrease of the excess flow. The above results were explained on the basis of an economizing activity of the sympathetic basal tone on available oxygen due to effects on the microvasculature as well as on the cell metabolism. The autonomic tone is also responsible for steeper reduction of blood flow after RH in the normal limbs due to enhanced myogenic reaction.

Animals↗
PubMed1981

The effect of the venom of Bitis gabonica on mesenteric and external iliac blood flow. - A preliminary study in the dog.

The activity of the venom of Bitis Gabonica on mesenteric and external iliac circulation was investigated in four anaesthetized dogs. Venom doses of 0.125, 0.25 and 0.50 mg/kg were injected intravenously with an interval of 30 minutes between two successive injections. Following the first and the second dose, a transient fall of the resistance was observed in the mesenteric and especially in the external iliac vascular bed. Then, mesenteric resistance returned to normal, whereas external iliac resistance increased noticeable above the control value. After the third injection the animals died in a state of severe hypotension. It is note-worthy that during the transient vasodilation, mesenteric flow did not increase proportionally to the reduction of the relevant resistance, owing to the fact that BP fell more than would have been expected from the mesenteric vasodilation. This discrepancy seemed to depend on a more conspicuous reduction of the resistance in other vascular beds as observed in the external iliac circulation.

Animals↗
PubMed1976

Isohemic blood volume expansion in normal and areflexive dogs.

The hemodynamic and renal responses to rapid intravascular volume expansion (VE) were studied in normal and areflexive dogs. "Isohemic" expansion was performed by infusing autologous blood (averaging 453 ml) thoroughly mixed with the circulating blood. In areflexive dogs cardiac output and arterial pressure doubled immediately after VE and fell back to control within 70 min; in normal dogs the circulatory response was less than one-third as great, but arterial pressure failed to return to control within 120 min. In the areflexive dogs, water, electrolyte, and total osmolar urinary output rose three- to fivefold after VE and declined thereafter, roughly following arterial pressure. In normal dogs the urine flow increased 40% immediately and rose further up to 70% in 60 min. No evidence for a natriuretic hormone was seen. It is concluded that mechanical factors are mainly responsible for the increased excretion of water and solutes after VE. Direct nervous reflexes to the kidney seemed to play a quantitatively minor role in the renal response.

Animals↗
PubMedDate not supplied

The heart as a biological clock: phase-locking between heart and efferent vagal activity.

Experiments were performed to evaluate whether the negative inotropic effect of efferent vagal stimulation is more strictly related to the number of stimuli falling with each cardiac cycle (St/c) or to the number of stimuli per second (St/s). Therefore, vagal stimulations were performed in anaesthetized dogs either with constant frequency (CONT), or with trains of 3 stimuli triggered by each atrial activation (SYNCHR). An atrial contractility index was measured while increasing heart rate by artificial heart pacing during CONT and SYNCHR vagal stimulations. The negative inotropic parasympathetic effect was reduced in the former protocol (St/s constant, St/c reduced) and did not change in the latter. It was concluded that the effect of vagal stimulation is more strictly related to St/c rather than to St/s. We suggest that the heart cycle operates as a biological clock with respect to cardiac vagal control.

Animals↗