Cardiovascular effects of central injection of acetylcholine in anaesthetized dogs: a role for vasopressin release

Abstract

1 The effect of an intracisternal injection of 20Ougkg-' of acetylcholine was studied on systolic and diastolic blood pressures, heart rate, and plasma levels of noradrenaline, adrenaline, vasopressin, plasma renin activity and atrial natriuretic factor in chloralose-anaesthetized dogs, 8 of which were normal and 7 with diabetes insipidus (deprived of vasopressin secretion by surgical lesion of the hypothalamoneurohypophysial system). 2 Acetylcholine significantly increased systolic and diastolic blood pressures in both groups of animals. However, the rise in blood pressure was significantly shorter lived in the dogs with diabetes insipidus. 3 Acetylcholine significantly increased plasma levels of noradrenaline but not adrenaline in control animals and in dogs with diabetes insipidus. Noradrenaline and adrenaline responses after acetylcholine were not different in the two groups of animals. 4 Acetylcholine induced a significant increase in vasopressin plasma levels only in control animals while in dogs with diabetes insipidus vasopressin remained at nearly undetectable levels. 5Acetylcholine significantly increased atrial natiuretic factor plasma levels only in control dogs. 6 Although plasma renin activity increased in both groups of animals after the i.c. injection of acetylcholine, this change was not significant in any group. 7 These results suggest that, in the anaesthetized dog, the central injection of acetylcholine induces a rise in blood pressure through both an increase in sympathetic outflow and a release of vasopressin.

Central cardiovascular effects of acetylcholine in the conscious dog

“…In fact, most of the available studies published on this topic have been performed in anaesthetized animals (for review, see Brezenoff & Giuliano, 1982). In anaesthetized animals, it is generally reported that ACh induces a rise in blood pressure mediated by an increase in both sympathetic tone and the release of AVP (Krstic & Djurcovic, 1978;Buccafusco & Brezenoff, 1979;Rascol et al, 1990). The central effects of cholinomimetic drugs on heart rate and Ad release are on the contrary extremely variable according to the literature.…”

“…injection of a single dose of 20 Mg kg-'; acetylcholine chloride (Lemotte and Boinot labs) dissolved into a 0.9% w/v NaCl solution in the ACh protocol. This dose was known to induce a mean rise in blood pressure of 30 mmHg in anaesthetized dogs according to previous comparable experiments performed in our laboratory (Rascol et al, 1990). The effects of i.c.…”

“…injection of ACh. The dose of Atro necessary to block the central muscarinic receptors (5 jg kg-') was chosen according to previous data obtained by our group in anaesthetized dogs (Rascol et al, 1990). The dose of Meca was chosen according to preliminary experiments performed in two anaesthetized dogs demonstrating that the pressor response induced by 200 jg kg-' of ACh injected intravenously (ganglionic nicotinic effect) was completely blocked by 250 jg kg-' of Meca injected by the same intravenous route.…”

“…We have previously reported that in chloralose anaesthetized dogs the intracisternal (i.c.) injection of ACh elicits a pressor response mediated by an increase in sympathetic outflow and vasopressin (AVP) release (Rascol et al, 1990). Much of the published work concerning the cardiovascular effects of the central injection of drugs acting at cholinoceptors have been performed in anaesthetized animals.…”

Cardiac Effect of Cholinesterase Inhibitors Used in Alzheimers Disease - from Basic Research to Bedside

“…Centrally administered ACh or cholinergic agents increase arterial BP [53] because of the increase in sympathetic nerve tone and the acceleration of vasopressin release [53][54][55]. Systemic injection of ChE inhibitor increases systolic and diastolic BP [27,56].…”