title: Parallel changes in ultrastructure and noradrenaline content of nerve terminals in rat vas deferens following transmitter release.
abstract: Transmural electrical stimulation and exposure to incubation media where some or all of the Na+ had been replaced with K+ were used to elicit transmitter release. Changes in noradrenaline content and ultrastructure of the nerve terminal varicosities in rat vas deferens were measured. Electrical stimulation in the presence of 4-aminopyridine had little effect, but high [K+] solutions caused a parallel reduction in noradrenaline content and the number of small dense-cored vesicles; large dense-cored vesicles showed no change, and small clear vesicles increased in number. In spite of a reduction in total vesicle number there was no evidence of expansion of the varicosity membrane. The parallel fall in noradrenaline content and in the number of small dense-cored vesicles suggests that the latter are the source of the released noradrenaline under the conditions of high [K+] stimulation we have used.
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D008297:Male; D008854:Microscopy, Electron; D009469:Neuromuscular Junction / Q000648:ultrastructure*; D009638:Norepinephrine / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000187:drug effects; D013572:Synaptic Vesicles / Q000648:ultrastructure; D014649:Vas Deferens / Q000294:innervation*
chemical_list: D011188:Potassium; D009638:Norepinephrine