Woodcock EA, Reyes N, Jacobsen AN, Du XJ. Inhibition of inositol(1,4,5)Trisphosphate generation by endothelin-1 during postischemic reperfusion: A novel antiarrhythmic mechanism.
Circulation 1999;
99:823-8. [PMID:
9989970 DOI:
10.1161/01.cir.99.6.823]
[Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND
Reperfusion of ischemic rat hearts in the presence of thrombin or norepinephrine but not endothelin-1 causes the generation of inositol 1,4,5-trisphosphate (Ins 1,4,5P3) and arrhythmias. The present study investigates the effect of endothelin-1 on these responses.
METHODS AND RESULTS
Ins 1,4,5P3 generation was quantified by use of [3H] labeling and high-performance liquid chromatography as well as by mass analysis. Twenty minutes of global ischemia followed by 2 minutes of reperfusion increased [3H]Ins 1,4,5P3 from 2828+/-265 to 5033+/-650 cpm/g tissue in the presence of thrombin 2.5 IU/mL and to 4561+/-286 cpm/g tissue in response to release of norepinephrine (n=4, P<0.01) in both cases. Reperfusion in the presence of endothelin-1 alone caused no change in Ins 1,4,5P3 (2762+/-240 cpm/g tissue), but when added together with thrombin or norepinephrine, endothelin-1 reduced the Ins 1,4,5P3 responses to 2313+/-197 and 1764+/-168 cpm/g tissue, respectively (n=4, P<0.01 in both cases). Similar inhibitory interactions between endothelin-1 10 nmol/L and thrombin 2.5 IU/mL were observed under normoxic conditions in nonperfused ventricle, eliminating the possibility that excessive vasoconstriction was responsible. In parallel studies, endothelin-1 suppressed the development of reperfusion arrhythmias initiated by either thrombin (ventricular fibrillation, 75% to 39%, n=16 to 18) or norepinephrine (83% to 8%, n=12 to 22) (P<0.01 in both cases).
CONCLUSIONS
Inhibition of Ins 1,4,5P3 generation during myocardial reperfusion by endothelin-1 represents a novel antiarrhythmic mechanism.
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