Regulation by Rab3A of an endogenous modulator of neurotransmitter release at mouse motor nerve endings.

Rab3A, a small GTP-binding protein attached to synaptic vesicles, has been implicated in several stages in the process of neurosecretion, including a late stage occurring just prior to the actual release of neurotransmitter. The inhibitory neuromodulator adenosine also targets a late step in the neurosecretory pathway. We thus compared neuromuscular junctions from adult Rab3A(-/-) mutant mice with those from wild-type mice with respect to: (a) the basic electrophysiological correlates of neurotransmitter release at different stimulation frequencies, and (b) the actions of exogenous and endogenous adenosine on neurotransmitter release in normal calcium solutions.

Inhibition of spontaneous acetylcholine secretion by 2-chloroadenosine as revealed by a protein kinase inhibitor at the mouse neuromuscular junction.

1. Previous studies have reported discrepancies in the potencies of A(1) adenosine receptor agonists at mouse motor nerve terminals. In addition, conflicting results on the role of protein kinase A (PKA) in mediating the inhibitory effects of A(1) receptor agonists have been published.