Ordoñez Fernández A, Hernandez Fernandez A, Borrego Dominguez JM, Gutierrez Carretero E, Muñoz García J, Prieto Rodriguez MF, Viloria Peñas MM. Coronary vasomotor disorders during hypoxia-reoxygenation: do calcium channel blockers play a protective role?
RESEARCH IN EXPERIMENTAL MEDICINE. ZEITSCHRIFT FUR DIE GESAMTE EXPERIMENTELLE MEDIZIN EINSCHLIESSLICH EXPERIMENTELLER CHIRURGIE 2000;
199:319-31. [PMID:
10945650 DOI:
10.1007/s004339900046]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
During heart surgery, myocardial dysfunction may occasionally appear when extracorporeal circulation is discontinued, causing serious haemodynamic disorders. Many mechanisms are involved in this hypoxia-reoxygenation syndrome. The aim of this experimental study was to characterize the vasomotor disorders that take place in the isolated porcine coronary artery during in vitro hypoxia-reoxygenation and to analyse the effect of nifedipine on them. Rings of porcine coronary artery were placed in an organ chamber connected to a system that recorded isometric forces. The vascular rings were divided into two groups: control group (no nifedipine) and study group (nifedipine, 10(-6) mol/l). The vascular rings were precontracted with 30 mmol/l KCl and then hypoxia-reoxygenation was induced. Control arterial rings showed important changes in coronary vasomotor tone: severe hypoxic contraction (from 14.48+/-1.16 g of stable contraction to 17.6+/-0.44 g after the imposition of hypoxia), and transient vasodilation during reoxygenation (69.9+/-10.1% of the maximum contraction achieved). The nifedipine group experienced a slow, progressive, vasodilation throughout the whole experiment (73+/-3.5% of the maximum contraction). Neither hypoxic vasospasm nor fluctuations of the coronary vascular tone occurred. Thus, at the end of the hypoxia, the control vessels presented a degree of contraction similar to the initial level. However, in the rings treated with nifedipine, the percentage of dilation was 73+/-3.5% (P<0.05). In the isolated porcine coronary artery with intact endothelium undergoing a situation of hypoxia-reoxygenation, we have detected transient vasoconstriction during the first period of hypoxia, followed by vasodilation during reoxygenation. The intracoronary administration of nifedipine prior to the imposition of hypoxia prevents hypoxic contraction, achieving a greater and more stable degree of coronary vasorelaxation during the complete process of hypoxia-reoxygenation.
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