Key result
Halothane induced a lower negative inotropic effect in senescent rats compared to adult rats (AF: 53% vs. 39% of baseline; P<0.01), whereas isoflurane induced a similar effect in both groups.
Why the study?
Do halothane and isoflurane have different inotropic and lusitropic effects on the myocardium of senescent rats compared to adult rats?
Do halothane and isoflurane have different inotropic and lusitropic effects on the myocardium of senescent rats compared to adult rats?
Absolute Event Rate: 53% vs 39%
p-value: p=< 0.01
Halothane has less pronounced negative inotropic and lusitropic effects in senescent rat myocardium compared to adult rats, whereas isoflurane's effects are similar across age groups.
Should not change anesthetic choice in elderly patients; leaves open translation of age-dependent effects to human myocardium.
BACKGROUND: Aging is associated with marked alterations in myocardial contraction and relaxation, whereas halogenated anesthetics depress myocardial contractility. However, their effects on aging myocardium are unknown. METHODS: Mechanical variables of left ventricular papillary muscles from adult and senescent rats (29 degrees C; pH 7.40; Ca2+ 1.0 or 0.5 mM; stimulation frequency, 12 pulses/min) were studied. The expression of genes coding for the alpha and beta-myosin heavy chain (MHC) and Ca2+ -ATPase of the sarcoplasmic reticulum (SR) were studied. The effects of halothane and isoflurane were studied. The inotropic effects were compared under low and high loads, using the maximum unloaded shortening velocity (Vmax) and maximum isometric active force (AF). The lusitropic effects were compared in isotonic and isometric conditions. RESULTS: Senescent rats had a decrease in contraction and relaxation velocities, associated with a reexpression of beta-MHC mRNAs and a decrease in SR Ca2+ -ATPase mRNAs. Halothane induced a lower negative inotropic effect in senescent rats (1.5 vol%, AF: 53 +/- 14% vs. 39 +/- 12% of baseline values; P < 0.01) whereas isoflurane induced a similar negative inotropic effect (1.5 vol%, AF: 81 +/- 7% vs. 87 +/- 7% of baseline values; NS). Halothane induced a negative lusitropic effect in isotonic conditions in adult, but not in senescent, rats. CONCLUSIONS: The inotropic and lusitropic effects of halothane were less important in senescent than in adult rats, whereas the effects of isoflurane were similar. These differences are probably related to differences in SR function and in the effects of halogenated anesthetics on the SR.
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Rozenberg et al. (2002) studied Aging myocardium. Halothane and Isoflurane vs. Adult rats was evaluated on Maximum isometric active force (AF) as a percentage of baseline (p=< 0.01). Halothane induced a lower negative inotropic effect in senescent rats compared to adult rats (AF: 53% vs. 39% of baseline; P<0.01), whereas isoflurane induced a similar effect in both groups.
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