On the Actions of Compounds Related to Dopamine at a Neurosecretory Synapse

Abstract

Royal (Dick) School of Veterinary Studies, Summerhall, Edinburgh EH9 1 QH I The effects of a number of substances related to dopamine, including all its methylated derivatives, were investigated on the membrane potential and response to nerve stimulation of cockroach salivary gland cells. 2 Only N-methyldopamine (epinine), N,N-dimethyldopamine and N,N-dimethylnoradrenaline, all with unsubstituted hydroxyl groups, directly resembled dopamine in producing a hyperpolarization which could be as large as that caused by maximal nerve stimulation. During the continued presence of these substances the hyperpolarization waned and responses to nerve stimulation declined. 3 Many of the compounds caused one or both of two other effects, namely an increase in the rate of 'spontaneous miniature hyperpolarizations' and an enhancement of the submaximal responses to single nerve stimuli. There were no obvious structural requirements for these effects.

Physiology of Invertebrate Salivary Glands

“…IoA). IoB), in the absence of nerve stimulation (Ginsborg, House & Turnbull, 19763;Bowser-Riley & House, 1976). IoB), in the absence of nerve stimulation (Ginsborg, House & Turnbull, 19763;Bowser-Riley & House, 1976).…”

On the receptors which mediate the hyperpolarization of salivary gland cells of Nauphoeta cinerea Olivier.

“…3B) and by 5-hydroxytryptamine (cf. Ginsborg, House & Turnbull, 1976;Silinsky, 1974). It is tempting to suppose that the effects are due to liberation of the transmitter, although evidently more direct experiments will be required to rule out the possibility of a post-synaptic origin (cf.…”

The aminergic control of cockroach salivary glands

“…A structure-activity study has shown that the two catechol OH groups are necessary but not sufficient for agonist action, because N-acetyldopamine is inactive (Ginsborg et al, 1976b).…”