Faculty Collaboration Database

Differential roles of myocardial Ca2+ channels and Na+/Ca2+ exchange in myocardial reperfusion injury in open chest dogs: relative roles during ischemia and reperfusion. Cardiovasc Res 1997 Dec;36(3):337-46

Date

04/16/1998

Pubmed ID

9534854

DOI

10.1016/s0008-6363(97)00187-9

Scopus ID

2-s2.0-0031455786 (requires institutional sign-in at Scopus site)   20 Citations

Abstract

OBJECTIVE: Compare the roles of Ca2+ channels and Na+/Ca2+ exchange in reperfusion injury (reperfusion ventricular fibrillation and myocardial stunning).

METHODS: Open chest dogs undergoing 15 minutes of left anterior descending coronary artery occlusion and 3 hours of reperfusion were randomized to controls or intracoronary infusions of the respective antagonists, nifedipine (50 micrograms/min) or amiloride (5 mg/min), according to five protocols: (A) 40 minutes before occlusion to 30 minutes after reperfusion; (B) 2 minutes before to 5 minutes after reperfusion; (C) 10 minutes before to 10 minutes after reperfusion (two step infusion for nifedipine only 5 micrograms/min during occlusion and 50 micrograms/min after reperfusion); and (D) 0 to 30 minutes after reperfusion. The role of Ca2+ channels was further investigated by infusing the agonist, Bay K 8644 (50 micrograms/min), alone or simultaneously with any protocol B, C, or D infusions altering both reperfusion ventricular fibrillation and myocardial stunning.

RESULTS: Effects of the agents on injury did not result from hemodynamic effects or alterations in blood flow. Amiloride had no effect on ventricular fibrillation. Only protocol A infusion of amiloride prevented myocardial stunning. In contrast, protocol A and B infusions of nifedipine prevented both myocardial stunning (p = ns vs. baseline, p < 0.01 vs. control) and ventricular fibrillation (0%, p < 0.01). Protocol C prevented reperfusion ventricular fibrillation, but not stunning (p = ns vs. control). Protocol D did not alter injury. Bay K 8644 co-treatment reversed the effects of Protocol B infusion of nifedipine. Ventricular fibrillation was common and postischemic function worst in dogs treated with Bay K 8644 alone (protocol B).

CONCLUSION: Myocardial Ca2+ channels contribute to both reperfusion ventricular fibrillation and stunning, whereas Na+/Ca2+ exchange contributes only to stunning. Inhibitors of myocardial Ca2+ channels are protective when infused in high doses just before reperfusion, whereas the efficacy of Na+/Ca2+ exchange inhibitors is dependent on pretreatment.

Author List

Smart SC, Sagar KB, Warltier DC

Author

David C. Warltier PhD Emeritus Professor in the Anesthesiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
Amiloride
Analysis of Variance
Animals
Calcium Channel Blockers
Calcium Channels
Dogs
Dose-Response Relationship, Drug
Myocardial Ischemia
Myocardial Reperfusion Injury
Myocardium
Nifedipine
Perfusion
Random Allocation
Sodium-Calcium Exchanger
Time Factors