FGF-2-induced negative inotropism and cardioprotection are inhibited by chelerythrine: involvement of sarcolemmal calcium-independent protein kinase C.

Abstract

Fibroblast growth factor-2 (FGF-2), administered to the isolated rat heart by perfusion and under constant pressure, is protective against ischemia-reperfusion (I-R). Here we have investigated whether FGF-2 cardioprotection: (a) is dependent on flow modulation; (b) is linked to effects on contractility; (c) is mediated by protein kinase C (PKC); and (d) is linked to PKC and/or mitogen activated protein kinase (MAPK) associated with the sarcolemma. The isolated rat heart was used as a model. Under conditions of constant flow FGF-2 induced significant improvement in recovery of contractile function during I-R. Under constant perfusion pressure, FGF-2 induced a negative inotropic effect (15% decrease in developed pressure). Chelerythrine, a specific PKC inhibitor, prevented both the FGF-2-induced negative inotropic effect before ischemia, and cardioprotection during I-R. FGF-2 induced a chelerythrine-preventable, five-fold increase in sarcolemmal calcium-independent PKC activity. It also increased the association of PKC subtypes -epsilon and -delta with sarcolemmal membranes, detected by Western blotting, as well as, for PKC delta, by immunolocalization. FGF-2 increased the association of PKC epsilon with the membrane fraction of adult cardiomyocyte in culture, confirming that it can affect PKC signaling in cardiomyocytes directly and in a manner similar to its effects in situ. Finally, FGF-2 induced increased active MAPK at sarcolemmal as well as cytosolic sites. Active sarcolemmal MAPK remained elevated when the FGF-2-induced protection was prevented by chelerythrine. In conclusion, we have provided evidence that cardioprotection by FGF-2 is independent of flow modulation. PKC activation mediates both the FGF-2-induced negative inotropic effect before ischemia and the cardioprotective effect assessed during reperfusion, suggesting a cause and effect relationship. Furthermore, FGF-2 cardioprotection is linked to targeting of sarcolemmal sites by calcium-independent PKC.

• Authors: R R Padua, P L Merle, B W Doble, C H Yu, P Zahradka, G N Pierce, V Panagia, E Kardami
• Journal: Journal of molecular and cellular cardiology (J Mol Cell Cardiol) Vol. 30 Issue 12 Pg. 2695-709 (Dec 1998) ISSN: 0022-2828 [Print] England
• PMID: 9990540 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Alkaloids
• Benzophenanthridines
• Enzyme Inhibitors
• Phenanthridines
• Fibroblast Growth Factor 2
• chelerythrine
• Protein Kinase C
• Calcium-Calmodulin-Dependent Protein Kinases
• Calcium

Topics

• Alkaloids
• Animals
• Benzophenanthridines
• Blotting, Western
• Calcium (pharmacology)
• Calcium-Calmodulin-Dependent Protein Kinases (drug effects)
• Cells, Cultured
• Cytosol (drug effects)
• Densitometry
• Enzyme Inhibitors (pharmacology)
• Fibroblast Growth Factor 2 (antagonists & inhibitors, pharmacology, physiology)
• Fluorescent Antibody Technique
• Male
• Membranes (drug effects)
• Myocardial Contraction (drug effects)
• Perfusion
• Phenanthridines (pharmacology)
• Protein Kinase C (antagonists & inhibitors, physiology)
• Rats
• Rats, Sprague-Dawley
• Reperfusion Injury (drug therapy, prevention & control)
• Sarcolemma (enzymology)
• Time Factors
• Ventricular Function, Left (drug effects)