Volatile cardioplegia: fast normothermic cardiac arrest induction and recovery with halothane in isolated rat hearts

To study the effect of halothane as a cardioplegic agent, ten Wistar rats were anesthetized by ether inhalation and their hearts were perfused in a Langgendorff system with Krebs-Henseleit solution (36 graus Celsius; 90 cm H2O pressure). After a 15-min period for stabilization the control values for heart rate, force (T), dT/dt and coronary flow were recorded and a halothane-enriched solution (same temperature and pressure) was perfused until cardiac arrest was obtained. The same Krebs-Henseleit solution was reperfused again and the parameters studied were recorded after 1,3,5,10,20 and 30 min. Cardiac arrest occurred in all hearts during the first two min of perfusion with halothanebubbled solution. One minute after reperfusion without halothane, the following parameters reported in terms of control values were obtained: 90.5 percent of control heart rate (266.9 + 43.4 to 231.5 + 71.0 bpm), 20.2 percent of the force (1.83 + 0.28 to 0.37 + 0.25 g), 19.8 percent of dT/dt (46.0 + 7.0 to 9.3 + 6.0 g/s) and 90.8 percent of coronary flow (9.9 + 1.5 to 9.4 + 1.5 ml/min). After 3 min of perfusion they changed to 99.0 percent heart rate (261.0 + 48.2), 98.9 percent force (1.81 + 0.33), 98.6 dT/dt (45.0 + 8.2) and 94.8 percent coronary flow (9.3 + 1.4). At 5 min 100.8 percent (267.0 + 40.6) heart rate, 105.0 percent (1.92 + 0.29) force and 104.4 percent (48.2 + 7.2) dT/dt were recorded and maintained without significant differences (P>0.01) until the end of the experiment. These data demonstrate that volatile cardioplegia with halothane is an effective technique for fast induction of and prompt recovery from normothermic cardiac arrest of the rat heart.

Reversäo pelo flumazenil do efeito cardiodepressor induzido pelo diazepam / Reversal by flumazenil of the cardiodepressant effect induced by diazepam

Foram estudados em sete ratos de raça wistar os efeitos do antagonista dos receptores GR (centrais). Flumazenil (8-fluoro-1,6-dihidro-5-metil-5-fenil-2h-1,4-benzodiazepina-3-carboxilato de etila) nas concentrações de dez mcg/ml, na depressÒo miocßrdica induzida pelo Diazepam (7-cloro-1,3-dihidro-1-metil-5-fenil-2h-1,4-benzodiazepin-1-ona) em doses de 100 mcg/ml em coraçöes isolados de ratos. Nestes experimentos foi utilizado o mÚtodo de LANGENDORFF e tÚcnica de GOTTLIEB e MAGNUS, modificada por PITCHON, utilizando como perfusato a soluçÒo de Krebs-Henseleit. Podemos constatar que nesta experimentaçÒo, o Flumazenil foi capaz de antagonizar os efeitos cardioinibidores do Diazepam. Estas açöes nos levam a sugerir a presença de receptores Gabarelacionados nos coraçöes isolados estudados.