Hemodynamic effects of levcromakalim in neonatal porcine pulmonary hypertension

Levcromakalim (LKM; a K-ATP channel opener) reverses hypoxic pulmonary vaso constriction in isolated pulmonary arteries and perfused lungs. This vasore laxation is blocked by glibenclamide (GLB; a K-ATP channel blocker). We eva luated the hemodynamic effect of LKM followed by GLB in a chronically instr umented neonatal porcine model of pulmonary hypertension, created by exposi ng piglets to hypoxia (n = 7) or heat-killed group B streptococci (GBS) (n = 6). Hypoxia increased pulmonary arterial pressure (PAP), which LKM decrea sed, and GLB subsequently increased in a dose-dependent manner. Systemic ar terial pressure (SAP) did not change with hypoxia but was also decreased by LKM and increased by GLB. GBS also led to increased PAP, but LKM significa ntly reduced only SAP, which was then increased by GLB. We conclude LKM is capable of reversing hypoxic, but not GBS-induced, pulmonary hypertension b ut lacks specificity for the neonatal pulmonary vasculature. Copyright (C) 2001 S. Karger AG, Basel.