Lack of effect of amiloride, furosemide, bumetanide and triamterene on pancreatic NaHCO3 secretion in pigs.

This study examines the effects of the Na entry blockers amiloride, furosemide, bumetanide and triamterene on pancreatic NaHCO3 secretion. The purpose of the study was to elucidate whether Na flux through a Na-H-antiport, a Na,K,Cl-symport or a Na-K(H)-antiport respectively, may be rate limiting for pancreatic NaHCO3 secretion. The effect of each drug on secretion was tested in four groups of six anaesthetized pigs (20-25 kg body wt) during supramaximal, intravenous secretin infusion (3.0 CU kg-1 body wt. h-1), following laparotomy and cannulation of the pancreatic duct. Secretion was measured over a wide range of arterial pH values, both before and after drug administration in each animal. Pancreatic NaHCO3 secretion averaged 268 (219-308) mumol min-1 at physiological arterial pH 7.40 in the control period. Neither amiloride (90 mg kg-1 body wt), furosemide (10 mg kg-1 body wt), bumetanide (0.6 mg kg-1 body wt) nor triamterene (25 mg kg-1 body wt) affected the rate of secretin-dependent NaHCO3 secretion or the relation between NaHCO3 secretion and arterial pH. It is concluded that Na flux through neither a Na-H-antiport, a Na,K,Cl-symport nor a Na-K(H)-antiport appears to be rate limiting for pancreatic secretion of NaHCO3.