Effect of intraventricular injection of transmitter substances and temperature on autonomic functions of conscious sheep.

Publisher Website
Google Scholar
Abstract
Changes in cardiovascular and renal functions after injection of noradrenaline [norepinephrine, NA], 5-hydroxytryptamine [5-HT] and carbachol into 1 lateral cerebral ventricle were studied in conscious sheep at ambient air temperatures of 0 and 40.degree. C. The dose rates used were known to produce predictable changes in thermoregulation in sheep. The changes in body temperature, respiratory frequency and shivering caused by the intracerebroventricular (ICV) injections of NA, 5-HT and carbachol were reported. The cardiovascular and renal responses of the sheep at both high and low ambient temperatures were consistent for each transmitter, indicating that the activities had no major dependence on the type of thermoregulatory response. ICV injection of NA increased heart rate and decreased pulse pressure but caused no change in mean arterial blood pressure (BP). Urine flow rate and Na, K and osmolal clearances were decreased, but solute-free water reabsorption was unaltered. ICV injection of 5-HT caused no significant changes in cardiovascular or renal function. ICV injection of carbachol increased systolic and diastolic BP heart rate and hematocrit. Na, K and osmolal clearances were increased after administration of carbachol. The changes in renal function after NA and carbachol injection were due to the concurrent changes in cardiovascular function.