NO induces a cGMP‐independent release of cytochrome c from mitochondria which precedes caspase 3 activation in insulin producing RINm5F cells

Abstract
Exposure of RINm5F cells to interleukin‐1β and to several chemical NO donors such as sodium nitroprusside (SNP), SIN‐1 and SNAP induce apoptotic events such as the release of cytochrome c from mitochondria, caspase 3 activation, Bcl‐2 downregulation and DNA fragmentation. SNP exposure led to transient activation of soluble guanylate cyclase (sGC) and prolonged protein kinase G (PKG) activation but apoptotic events were not attenuated by inhibition of the sGC/PKG pathway. Prolonged activation of the cGMP pathway by exposing cells to the dibutyryl analogue of cGMP for 12 h induced both apoptosis and necrosis, a response that was abolished by the PKG inhibitor KT5823. These results suggest that NO‐induced apoptosis in the pancreatic β‐cell line is independent of acute activation of the cGMP pathway.