Anderson KE, Dart AM, Woodcock EA. Inositol phosphate release and metabolism during myocardial ischemia and reperfusion in rat heart.
Circ Res 1995;
76:261-8. [PMID:
7834837 DOI:
10.1161/01.res.76.2.261]
[Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A detailed study of the effects of global myocardial ischemia and reperfusion on inositol phosphate release and metabolism has been undertaken by using isolated perfused rat hearts. Ischemia for longer than 5 minutes caused a cessation of inositol phosphate production, with inositol phosphates initially present accumulating as isomers of inositol monophosphate. This inhibition was independent of norepinephrine. In contrast, 2-minute reperfusion following 20-minute ischemia produced a rapid and transient release of inositol phosphates that was dependent on the release of norepinephrine and mediated by alpha 1-adrenergic receptors. By a number of criteria, this reperfusion response was different from the norepinephrine response in normoxic tissue. First, total release of inositol phosphates was greater (466 +/- 37 compared with 345 +/- 29 cpm/mg protein, P < .05). Second, inositol 1,4,5-trisphosphate was released with postischemic reperfusion (103 +/- 18 to 207 +/- 11 pmol/mg protein), whereas release was not detected in normoxic myocardium. In agreement with this, neomycin (0.5 and 5 mmol/L) inhibited inositol phosphate release only under reperfusion conditions. Third, the reperfusion response, unlike the response in nonischemic tissue, required extracellular Ca2+. Longer periods of reperfusion resulted in a return to a pattern of inositol phosphate release that was not different from that seen in normoxic tissue. The rapid and transient release of inositol 1,4,5-trisphosphate at 2-minute postischemic reperfusion provides an explanation for the enhanced role of alpha 1-adrenergic receptors under these conditions and suggests an important role for this compound in initiating reperfusion-induced pathological events.
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