Ionic requirements in histamine-evoked potassium efflux in guinea pig pancreas.
Guinea pig pancreatic segments were superfused during 10 min with physiological saline solutions containing 10(-6) M acetylcholine (ACh) or histamine (10(-3)-10(-6) M) and the potassium concentration in the effluent [K+]o) was measured by flame photometry. Histamine evoked a transient increase in [K/]o. The removal of calcium from the superfusing solution and addition of 10(-4) M EGTA caused a significant reduction in the histamine-evoked potassium outflow. Replacement of chloride (Cl-) in the physiological salt solution by nitrate (NO3-) caused a significant reduction in the histamine-evoked potassium release. However, when Cl- was replaced by bromide (Br-) the response to histamine was unaffected. Pre-treatment of pancreatic segments with furosemide (10(-4 M) or ouabain (10(-3) M) caused a marked reduction in the histamine-induced potassium release. The results suggest that ionic requirements in histamine-evoked potassium release are the same as those in acetylcholine-evoked potassium efflux.
Rosado
J A
JA
Departamento de Fisiología, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain.
García
L J
LJ
Salido
G M
GM
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005665:Furosemide / Q000494:pharmacology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D008297:Male; D009924:Organ Culture Techniques; D010042:Ouabain / Q000494:pharmacology; D010179:Pancreas / Q000187:drug effects* / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*
D002712:Chlorides; D004232:Diuretics; D004791:Enzyme Inhibitors; D010042:Ouabain; D005665:Furosemide; D006632:Histamine; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium