Effects of nerve stimulation on enzyme secretion from the in vitro rat pancreas and 3H-release after preincubation with catecholamines.
In the presence of the cholinergic antagonist atropine, electrical field stimulation (FS) (5-20 Hz) caused a marked, reversible increase in the amylase output from superfused rat pancreatic segments. Adrenaline and noradrenaline evoked dose-dependent increases in amylase output which were similar to those produced by FS. The FS- and catecholamine-evoked amylase secretions were abolished by the beta-adrenergic antagonist propranolol. The FS-evoked secretion could be abolished by either the removal of external Ca2+ or the application of tetrodotoxin (TTX, 2 X 10(-6) M). FS also resulted in a reversible increase in the fractional efflux of tritium (3H) from rat pancreatic tissues preincubated with either 3H-noradrenaline or 3H-adrenaline. The effects of FS (5-20 Hz) on 3H efflux were abolished by TTX (2 X 10(-6) M). TTX had no effect on the enhancement of 3H efflux caused by elevation of external potassium concentration (high K+, 75 mM). Removal of superfusate Ca2+ completely abolished both the FS- and high K+-induced increases in 3H efflux. These observations suggest that intrinsic nerve stimulation (i.e. FS) results in the Ca2+-dependent release of sympathetic neurotransmitter, noradrenaline, which has a direct secretory action on the rat pancreas. Furthermore, the findings suggest that adrenaline can be taken up by nervous elements. This raises the possibility that uptake and re-release of circulating adrenaline might contribute to the control of rat pancreatic enzyme secretion by the adrenergic nervous system.
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002799:Cholinergic Fibers / Q000502:physiology; D004558:Electric Stimulation; D004837:Epinephrine / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology*; D010179:Pancreas / Q000201:enzymology* / Q000294:innervation / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology; D014316:Tritium
D014316:Tritium; D013779:Tetrodotoxin; D001285:Atropine; D011433:Propranolol; D000681:Amylases; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine