Effects in the autonomic nervous system

The effects of the cholinesterase inhibitors, DFP and physostigmine, on the autonomic nervous system were examined in the dog [83]. Under conditions in which muscarinic effects are blocked by atropine, cholinergic nicotinic effects do not appear to be potentiated by cholinesterase inhibition. However, when autonomic ganglia are blocked with hexamethoipium or meca-mylamine, the responses to muscarinic stimulation are markedly potentiated. 

This type of analysis demonstrates the predominant effect of cholinesterase inhibition by these compounds in the autonomic nervous system of the dog to be manifest at post-ganglionic parasympathetic nerve-endings. 

Centrally mediated autonomic effects (i) Cardiovascular effects 

The intravenous injection of neostigmine at high doses (1(X) gg/kg) after ganglionic blockade in the anaesthetised dog elicits a pressor response [96], and McEwen [97] reported intravenous injections of physostigmine at doses of 1(X) pg to 1 mg in atropinised rats (approximating 0-5 to 5 mg/kg) to elicit 

The decrease in the content of glycogen in the brain of rats due to physostigmine [103] is blocked by both atropine and propranalol. Electrical stimulation of the ventromedial hypothalamic nucleus of rabbits from which the sympathetic outflow arises causes a marked hyperglycaemia and decrease in liver glycogen [104]. 

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According to their mode of action the Rauvolfia-alkaloids can be divided into two gronps the centrally acting reserpine, rescinnamine, and deserpidine and the peripherally acting yohimbine, raubasine and ajmaline. The blood pressure lowering effect is dne to an inhibition of the sympathomimetic effects in the autonomic nervous system and has a long latency and duration. The effect is dne to depletion of the serotonin and... 

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