The autoregulation of the coronary flow of the isolated rat heart after NO-synthase blockade
Solodkov, A.P.; Bozhko, A.P.; Shebeko, V.I.; Rodionov, I.I.
Biulleten' Eksperimental'noi Biologii i Meditsiny 116(9): 242-244
1993
ISSN/ISBN: 0365-9615 PMID: 7509647 Document Number: 413395
The experiments were performed on 67 rat hearts isolated by the Langendorff method. Perfusion pressure (PP) was stepwise increased from 40 to 120 mm Hg. It was found that NO-synthase blockade by NG-monomethyl-L-arginine (NG-MMLA) decreased volume velocity coronary flow (VVCF) at PP 40 and 60 mm Hg, autoregulation index and shifted the onset of effective autoregulation to the right. In cases of high coronary tone, caused by introduction of pituitrine, the autoregulation and its effectiveness was unchanged. The combination of NG-MMLA and pituitrine decreased the autoregulation index again. In cardiac perfusion under constant pressure, the value of maximal hyperemic coronary flow after introduction of NG-MMLA was decreased by 30-57%, and as a result the coronary reserve was decreased by 28.3%. Thus, NO, which released from endothelium of coronary vessels plays a significant role in mechanism of coronary autoregulation.