Alterations of the pancreatic secretory responses to secretin and to the ionophore A23187 by reserpine: a calcium-mediated phenomenon?
This study was undertaken to further characterize the secretory response of the rat pancreas after reserpine treatment. Rats were given reserpine (1 mg kg-1 day-1 i.p.) or vehicle for 7 days. To distinguish between specific effects of reserpine and those related to secondary malnutrition caused by the drug, the secretory response of a group of pair-fed (PF) animals to reserpine was also investigated. Amylase release from dispersed pancreatic acini, prepared from control (C), PF and reserpine-treated (R) rats were used to evaluate functional secretory capacity. Reserpine and pair-feeding caused reduced responses of pancreatic acini to secretin. The pair-feeding-altered secretin response was greatly improved by increasing extracellular Ca2+ concentration, whereas a slight improvement was noticed in the R group. Reserpine significantly reduced the secretory response to the ionophore A23187 at concentrations above 5 x 10(-7) M in 1.25 mM Ca2+; in 2.5 mM Ca2+, the response to the ionophore was significantly higher in the R group than in C at all ionophore concentrations. Furthermore, at 2 x 10(-7) M ionophore, the secretory response to secretin in the R group became significantly higher than that in the C group but comparable to that of the control+ionophore. In conclusion, reserpine affects the secretory response to secretin as did pre-exposure of pancreatic acini to a high concentration of carbamylcholine. The modified secretory response to the ionophore following reserpine treatment indicates that reserpine may act as a 'Ca2+ entry mechanism' antagonist which may explain the partial reduction in the secretin response.
Benrezzak
O
O
Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Qué., Canada.
Bérubé
F L
FL
St-Jean
L
L
Morisset
J
J
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000037:antagonists & inhibitors*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004435:Eating; D008297:Male; D010179:Pancreas / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012110:Reserpine / Q000494:pharmacology*; D012633:Secretin / Q000037:antagonists & inhibitors*
D002121:Calcium Channel Blockers; D012633:Secretin; D000001:Calcimycin; D012110:Reserpine; D000681:Amylases; D002118:Calcium