title: Cholinergic-induced electrolyte transport in rat parotid acini.
abstract: Secretory responses of parotid acini occurring within 10 sec following cholinergic stimulation were characterized. 1. Measurement of membrane potentials by means of the fluorescent dye diSC3-(5) revealed a value of approximately -59 mV, which remained unaffected on stimulation. 2. Stimulation caused a rapid net loss of 42K+ that was strongly inhibited by the "maxi" K+-channel inhibitor "charybdotoxin" present in scorpion venom. 3. It was calculated that the number of open "maxi" K+-channels per cell was approximately 40 in the unstimulated state and approximately 3000 in the stimulated state. 4. Stimulation caused a transient decrease in the acinar ATP content. 5. Intracellular pH (pHi) measured by means of the fluorescent dye, BCECF, was dependent upon the presence of extracellular HCO3- as well as Na+. Under physiological conditions pHi was 7.27 and stimulation caused a transient decrease of 0.1 pH units due to HCO3- efflux. The decrease was followed by pHi recovery mediated by a Na+/H+ exchange mechanism.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D004553:Electric Conductivity; D004573:Electrolytes / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D010306:Parotid Gland / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology*; D012463:Saliva / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D004573:Electrolytes; D015221:Potassium Channels; D011950:Receptors, Cholinergic; D000255:Adenosine Triphosphate; D002217:Carbachol; D011188:Potassium