Cyclic GMP reduces ventricular myocyte stunning after simulated ischemia-reperfusion.

Abstract

We tested the hypothesis that the second messenger activated by nitric oxide, cyclic GMP, would reduce the effects of myocyte stunning following simulated ischemia-reperfusion and that this was related to cyclic GMP protein kinase. Ventricular cardiac myocytes were isolated from New Zealand White rabbits (n = 8). Cell shortening was measured by a video edge detector and protein phosphorylation was determined autoradiographically after SDS gel electrophoresis. Cell shortening data were acquired at: (i) baseline followed by 8-Bromo-cGMP 10(-6) M (8-Br-cGMP) and then KT 5823 10(-6) M (cyclic GMP protein kinase inhibitor) and (ii) simulated ischemia (20 min of 95% N(2)-5% CO(2) at 37 degrees C) followed by simulated reperfusion (reoxygenation) with addition of 8-Br-cGMP 10(-6) M followed by KT 5823 10(-6) M, (iii) addition of 8-Br-cGMP prior to ischemia followed by the addition of KT 5823 10(-6) M after 30 min of reoxygenation. In the control group, 8-Br-cGMP 10(-6) M decreased percentage shortening (%short) (5.0 +/- 0.6 vs 3.8 +/- 0. 4) and the maximum velocity (V(max), microm/s) (48.6 +/- 6.9 vs 40.2 +/- 6.4). KT 5823 10(-6) M added after 8-Br-cGMP partially restored %short (4.6 +/- 0.5) and V(max) (46.6 +/- 8.0). After stunning, baseline myocytes had decreased %short (3.4 +/- 0.2) and V(max) (36. 0 +/- 4.2). After the addition of 8-Br-cGMP, the %short (2.7 +/- 0. 2) and V(max) (27.6 +/- 2.5) decreased further. The addition of KT 5823 did not change either the %short or the V(max). The myocytes with 8-Br-cGMP during ischemia had increased %short (4.2 +/- 0.2) and V(max) (37.2 +/- 3.4) when compared to the stunned group. The addition of KT 5823 did not significantly alter %short (3.3 +/- 0.4) or V(max) (29.2 +/- 5.0) in the myocytes pretreated with 8-Br-cGMP. Protein phosphorylation was increased by 8-Br-cGMP in control and stunned myocytes. KT 5823 blocked this effect in control but not stunned myocytes, suggesting some change in the cyclic GMP protein kinase. Ischemia-reperfusion produced myocyte stunning that was reduced when 8-Br-cGMP was added prior to but not after ischemia.

• Authors: A Gandhi, L Yan, P M Scholz, M W Huang, H R Weiss
• Journal: Nitric oxide : biology and chemistry (Nitric Oxide) Vol. 3 Issue 6 Pg. 473-80 (Dec 1999) ISSN: 1089-8603 [Print] United States
• PMID: 10637126 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
• Copyright: Copyright 1999 Academic Press.

Chemical References

• Alkaloids
• Carbazoles
• Enzyme Inhibitors
• Indoles
• Phosphoproteins
• KT 5823
• 8-bromocyclic GMP
• Cyclic GMP

Topics

• Alkaloids (pharmacology)
• Animals
• Carbazoles
• Cell Size (drug effects)
• Cells, Cultured
• Cyclic GMP (analogs & derivatives, pharmacology, physiology)
• Enzyme Inhibitors (pharmacology)
• Heart (drug effects, physiology)
• Heart Ventricles
• Indoles
• Myocardial Ischemia (physiopathology)
• Myocardial Reperfusion
• Myocardial Stunning (physiopathology)
• Myocardium (cytology)
• Phosphoproteins (metabolism)
• Phosphorylation
• Rabbits