First molecular evidence that inositol trisphosphate signaling contributes to infarct size reduction with preconditioning.


Considerable attention has focused on the role of protein kinase C (PKC) in triggering the profound infarct-sparing effect of ischemic preconditioning (PC). In contrast, the involvement of inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)], the second messenger generated in parallel with the diacylglycerol-PKC pathway, remains poorly understood. We hypothesized that, if Ins(1,4,5)P(3) signaling [i.e., release of Ins(1,4,5)P(3) and subsequent binding to Ins(1,4,5)P(3) receptors] contributes to PC-induced cardioprotection, then the reduction of infarct size achieved with PC would be attenuated in mice that are deficient in Ins(1,4,5)P(3) receptor protein. To test this concept, hearts were harvested from 1) B6C3Fe-a/a-Itpr-1(opt+/-)/J mutants displaying reduced expression of Ins(1,4,5)P(3) receptor-1 protein, 2) Itpr-1(opt+/+) wild types from the colony, and 3) C57BL/6J mice. All hearts were buffer-perfused and randomized to receive two 5-min episodes of PC ischemia, pretreatment with d-myo-Ins(1,4,5)P(3) [sodium salt of native Ins(1,4,5)P(3)], the mitochondrial ATP-sensitive K(+) channel opener diazoxide, or no intervention (controls). After the treatment phase, all hearts underwent 30-min global ischemia followed by 2 h of reperfusion, and infarct size was delineated by tetrazolium staining. In both wild-type and C57BL/6J cohorts, area of necrosis in hearts that received PC, d-myo-Ins(1,4,5)P(3), and diazoxide averaged 28-35% of the total left ventricle (LV), significantly smaller than the values of 52-53% seen in controls (P < 0.05). In contrast, in Itpr-1(opt+/-) mutants, protection was only seen with diazoxide: neither PC nor d-myo-Ins(1,4,5)P(3) limited infarct size (52-58% vs. 56% of the LV in mutant controls). These data provide novel evidence that Ins(1,4,5)P(3) signaling contributes to infarct size reduction with PC.

4 Figures and Tables


Citations per Year

226 Citations

Semantic Scholar estimates that this publication has 226 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Przyklenk2006FirstME, title={First molecular evidence that inositol trisphosphate signaling contributes to infarct size reduction with preconditioning.}, author={Karin Przyklenk and Michelle A Maynard and Peter Whittaker}, journal={American journal of physiology. Heart and circulatory physiology}, year={2006}, volume={291 4}, pages={H2008-12} }