ATP-SENSITIVE K+ CHANNELS ARE GRADUALLY RECRUITED IN THE VASODEPRESSOR RESPONSE TO ADENOSINE IN SPINALLY-ANESTHETIZED DOGS

Vasodepressor mechanisms of adenosine were investigated in spinally-anesthetized dogs. An i.v.-infusion of adenosine (0.1-10 mumol/kg/min) caused a slowly developing and sustained decrease in blood pressure (BP). This vasodepression was antagonized by glibenclamide, a blocker of ATP-sensitive K+ (K(ATP)) channels. On the other hand, a transient decrease in BP caused by a single bolus i.v.-injection of adenosine was not antagonized by glibenclamide in our previous study. These results suggested that the opening of K(ATP) channels is gradually recruited in the vasodepressor mechanisms for adenosine-induced sustained vasodepression.