HIV protease inhibitors elicit volume-sensitive Cl− current in cardiac myocytes via mitochondrial ROS

Abstract HIV protease inhibitors (HIV PI) reduce morbidity and mortality of HIV infection but cause multiple untoward effects. Because certain HIV PI evoke production of reactive oxygen species (ROS) and volume-sensitive Cl− current (ICl,swell ) is activated by ROS, we tested whether HIV PI stimulate ICl,swell in ventricular myocytes. Ritonavir and lopinavir elicited outwardly rectifying Cl− currents under isosmotic conditions that were abolished by the selective ICl,swell -blocker DCPIB. In contrast, amprenavir, nelfinavir, and raltegravir, an integrase inhibitor, did not modulate ICl,swell acutely. Ritonavir also reduced action potential duration, but amprenavir did not. ICl,swell activation was attributed to ROS because ebselen, an H2 O2 scavenger, suppressed ritonavir- and lopinavir-induced ICl,swell . Major ROS sources in cardiomyocytes are sarcolemmal NADPH oxidase and mitochondria. The specific NADPH oxidase inhibitor apocynin failed to block ritonavir- or lopinavir-induced currents, although it blocks ICl,swell elicited by osmotic swelling or stretch. In contrast, rotenone, a mitochondrial e− transport inhibitor, suppressed both ritonavir- and lopinavir-induced ICl,swell . ROS production was measured in HL-1 cardiomyocytes with C-H2 DCFDA-AM and mitochondrial membrane potential ( ΔΨm ) with JC-1. Flow cytometry confirmed that ritonavir and lopinavir but not amprenavir, nelfinavir, or raltegravir augmented ROS production, and HIV PI-induced ROS production was suppressed by rotenone but not NADPH oxidase blockade. Moreover, ritonavir, but not amprenavir, depolarized ΔΨm . These data suggest ritonavir and lopinavir activated ICl,swell via mitochondrial ROS production that was independent of NADPH oxidase. ROS-dependent modulation of ICl,swell and other ion channels by HIV PI may contribute to some of their actions in heart and perhaps other tissues.