| Popis: |
The effects of nitrous oxide on variables of contractility and relaxation were analyzed in isolated ferret right ventricular papillary muscles. Each mechanical variable, in isometric, isotonic, and zero-load-clamped twitches, was compared to the average value of that variable in control conditions (50% nitrogen in oxygen), before and after equilibration with 20%, 30% and 50% nitrous oxide in 50% oxygen. Nitrous oxide caused a concentration-dependent decrease in contractility under all loading conditions, with minor changes in relaxation. The intracellular calcium transient was detected with the Ca(++)-regulated photoprotein aequorin. The change in aequorin luminescence on exposure to nitrous oxide suggests that the negative inotropic effect of nitrous oxide is due to a decrease in calcium availability with no effect on myofibrillar responsiveness to calcium. |
