Mitochondrial Uncoupler Carbonyl Cyanide M-chlorophenylhydrazone Induces Vasorelaxation Without Involving K Channel Activation in Smooth Muscle Cells of Arteries

Background And Purpose: The effects and mechanisms of chemical mitochondrial uncouplers on vascular function have never been identified. Here, we characterized the effects of the typical mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) on vascular function in rat mesenteric arteries and aorta and elucidated the potential mechanisms.

Experimental Approach: Isometric tension of mesenteric artery and thoracic aorta was recorded by using a multiwire myograph system. Protein levels were measured by western blot analyses. Cytosolic [Ca ] , mitochondrial ROS (mitoROS) and mitochondrial membrane potential of smooth muscle cells (A10) were measured by laser scanning confocal microscopy.

Key Results: Acute treatment with CCCP relaxed phenylephrine (PE)- and high K (KPSS)-induced constriction of rat mesenteric arteries with intact and denuded endothelium. Pretreatment with CCCP prevented PE- and KPSS-induced constriction of rat mesenteric arteries with intact and denuded endothelium. Similarly, CCCP prevented PE- and KPSS-induced constriction of rat thoracic aorta. CCCP increased the cellular ADP/ATP ratio in vascular smooth muscle cells (A10) and activated AMPK in A10 cells and rat thoracic aorta tissues. CCCP-induced aorta relaxation was attenuated in AMPK α1 knockout (-/-) mice. SERCA inhibitors thapsigargin and cyclopiazonic acid (CPA) but not the K channel blocker glibenclamide partially inhibited CCCP-induced vasorelaxation in endothelium-denuded rat mesenteric arteries. CCCP increased cytosolic [Ca ] , mitoROS production and depolarized mitochondrial membrane potential in A10 cells. FCCP, the analogue of CCCP, had similar vasoactivity as CCCP in rat mesenteric arteries.

Conclusions And Implications: CCCP induces vasorelaxation by a mechanism that does not involve K channel activation in smooth muscle cells of arteries.