Functional Modulation of Cardiac ATP-Sensitive K(+) Channels.
ATP-sensitive K+ (KATP) channels are inhibited by intracellular ATP, but MgATP is necessary to maintain the channel activity. Numerous cofactors modulate channel function. K+ channel openers activate and sulfonylureas inhibit KATP channels. The structure of cardiac KATP channel is a complex of mainly KIR6.2 and SUR2a. Activation of cardiac KATP channels contributes to action potential shortening during ischemia and plays a role in cardioprotection.
In this article, we study a piecewise smooth dynamical system inspired by a previous reduced system modeling compartimentalized brain metabolism. The piecewise system allows the introduction of an autoregulation induced by a feedback of the extracellular or capillary Lactate concentrations on the Capillary Blood Flow. New dynamical phenomena are uncovered and we discuss existence and nature of two equilibrium points, attractive segment, boundary equilibrium and periodic orbits depending of the Capillary Blood Flow.