Effect of ACh and calmodulin inhibitor on O2 transfer from exocrine pancreatic microvessels of rats.
Effects of acetylcholine (ACh) and calmodulin (CaM) inhibitor, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7), on the rate of O2 release (Ro2) from single exocrine pancreatic microvessels of anesthetized rats were investigated with dual-spot microspectroscopy. The surface of the pancreas was superfused with Krebs-Henseleit buffer containing various concentrations of ACh and/or W-7. Superfusion of ACh (> or = 20 microM) elevated Ro2 as well as pancreatic secretion approximately 2.5 times higher than that of control level, whereas superfusion of W-7 (> or = 100 microM) reduced approximately 50%. In both cases, O2 inflow in single microvessels, as quantified by oxyhemoglobin inflow into the microvessels, was maintained at control level. On the other hand, superfusion of both ACh and W-7 did not modify Ro2 and pancreatic secretion, despite significant reduction in O2 inflow. These results indicate that 1) the ACh-induced elevation of O2 release from single microvessels is accomplished by increased O2 extraction instead of increased O2 inflow in the microvessels, and 2) the activity of a W-7-sensitive Ca2+ binding protein, most likely CaM, is responsible for half of the microvascular O2 transfer and of the pancreatic exocrine secretion.
Seiyama
A
A
Department of Physiology, Osaka University, Medical School, Japan.
Kosaka
H
H
Shiga
T
T
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D004305:Dose-Response Relationship, Drug; D008297:Male; D008833:Microcirculation; D010100:Oxygen / Q000097:blood* / Q000378:metabolism; D010179:Pancreas / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013449:Sulfonamides / Q000494:pharmacology*
D002147:Calmodulin; D013449:Sulfonamides; C017967:W 7; D000109:Acetylcholine; D010100:Oxygen