Colchicine inhibits the effects of secretin on pancreatic duct cell tubulovesicles and HCO3- secretion in the pig.
Secretin stimulation clears the cytoplasm of intralobular pancreatic duct cells in pigs of tubulovesicles and causes these cells to secrete HCO3- into the pancreatic juice. To determine whether the clearance of cytoplasmic tubulovesicles involves the microtubule system and is important for initiation of HCO3- secretion, the effect of the microtubule poison colchicine on duct cell morphology and pancreatic HCO3- secretion was measured in anaesthetized pigs. Before colchicine, secretin reduced the density of tubulovesicles in the cytoplasm of pancreatic duct cells from 92 +/- 8 U to 8 +/- 2 U and initiated pancreatic secretion of 176 +/- 21 mumols min-1 HCO3-. After colchicine, secretin failed to lower duct cell tubulovesicle density and caused the secretion of only 77 +/- 14 mumols min-1 HCO3-. By contrast, lumicolchicine, an isomer of colchicine that does not affect microtubules, did not inhibit pancreatic HCO3- secretion. Colchicine did not reduce carbonic anhydrase or Na,K-ATPase activities in in-vitro assays. The clearance of tubulovesicles from the cytoplasm of pancreatic duct cells therefore seems to be microtubule-dependent and important for the pancreatic HCO3- secretion.
Veel
T
T
University of Oslo, Institute for Experimental Medical Research, Norway.
Buanes
T
T
Engeland
E
E
Raeder
M G
MG
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002256:Carbonic Anhydrases / Q000378:metabolism; D003078:Colchicine / Q000494:pharmacology*; D002479:Inclusion Bodies / Q000187:drug effects* / Q000502:physiology; D008162:Lumicolchicines / Q000494:pharmacology; D010183:Pancreatic Ducts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D012633:Secretin / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013552:Swine / Q000378:metabolism*
D001639:Bicarbonates; D008162:Lumicolchicines; D012633:Secretin; D002256:Carbonic Anhydrases; D000254:Sodium-Potassium-Exchanging ATPase; D003078:Colchicine