RESUMO
High buffer cardioplegia may provide protection against ischemic damage by reducing the extent of intracellular acidosis. Secondary cardioplegia may improve postischemic recovery by restoration of high energy phosphates, ionic gradients, and intracellular pH. To test these hypotheses, pig hearts were arrested with high buffer (150 mM MOPS) cardioplegia or modified St. Thomas' solution II and then kept ischemic at 12 degrees C for 8 h. High energy phosphates and intracellular pH were followed during the period of ischemia, using 31P nuclear magnetic resonance spectroscopy, and functional recovery was followed during reperfusion. The hearts arrested by high buffer cardioplegia showed significantly higher intracellular pH than hearts preserved with St. Thomas' solution, but there were no significant differences in high energy phosphates. There were no significant differences in functional recovery. We found, however, that secondary cardioplegia abolished ventricular fibrillation, and resulted in improved functional recovery after 8 h of ischemic preservation compared with the hearts reperfused with Krebs-Henseleit solution alone. Our results suggest that despite attenuating the decreases in intracellular pH, high buffer cardioplegia does not improve recovery following 8 h of preservation at 12 degrees C. Secondary cardioplegia reduces the incidence of ventricular fibrillation and improves postischemic functional recovery of the myocardium.
Assuntos
Soluções Tampão , Cálcio/uso terapêutico , Soluções Cardioplégicas/uso terapêutico , Doença das Coronárias/prevenção & controle , Coração/fisiologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Trifosfato de Adenosina/metabolismo , Animais , Bicarbonatos/uso terapêutico , Cloreto de Cálcio/uso terapêutico , Doença das Coronárias/tratamento farmacológico , Doença das Coronárias/metabolismo , Criopreservação/métodos , Relação Dose-Resposta a Droga , Feminino , Coração/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Líquido Intracelular/metabolismo , Magnésio/uso terapêutico , Espectroscopia de Ressonância Magnética , Masculino , Traumatismo por Reperfusão Miocárdica/tratamento farmacológico , Miocárdio/metabolismo , Preservação de Órgãos/métodos , Fosfocreatina/análogos & derivados , Fosfocreatina/metabolismo , Fósforo , Cloreto de Potássio/uso terapêutico , Cloreto de Sódio/uso terapêutico , SuínosRESUMO
During the last two decades the search for alternatives to whole blood transfusions has led to promising developments in the field of erythrocyte substitutes. Hemoglobin solutions free of fragments of erythrocyte stroma and fluorocarbon emulsions are not blood-type-specific and appear likely to satisfy some proportion of our blood requirements. Both must be modified before becoming clinically useful. The oxygen affinity of the hemoglobin solution must be reduced and its intravascular persistence improved. Fluorocarbons cannot yet contribute significantly to the oxygen supply unless the patient breathes hyperbaric oxygen. Recent advances are leading to solutions for these problems.