Summary
Currently there is considerable interest in the metabolism of the immature myocardium and in particular the mechanisms underlying its greater tolerance to ischemia than that of the adult heart. In order to investigate whether this tolerance is sex-related, we compared the recovery of function in isolated hearts from male and female neonatal rats (three to five days old) following 60 min of normothermic global ischemia and 30 min of reperfusion (n=8 per group). The female hearts exhibited significantly better (p<0.05) recovery of rate (81±5% vs. 65±5%) and the rate-pressure product (73±9% vs. 37±8%), and a tendency towards better recovery of contractile function (left ventricular developed pressure, 89±9% vs. 59±12%; dP/dt, 84±12% vs. 54±13%). This evidence for greater resistance of female hearts to ischemic injury was supported by a delayed onset of contracture (mean time to onset, 29.4±2.7 min vs. 24.9±2.6 min). The loss in left ventricular compliance during ischemia and reperfusion was also smaller in the female hearts (increase in left ventricular end diastolic pressure, 6.5±1.2 mm Hg vs. 13.6±3.8 mm Hg). These results suggest that there may be sex-related differences in the tolerance of immature hearts to ischemia, a factor which should be taken into account in the design and interpretation of experimental studies.
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References
Bove EL, Stammers AH (1986) Recovery of left ventricular function after hypothermic global ischemia, age-related differences in the isolated working rabbit heart. J Thorac Cardiovasc Surg 91:115–122
Grice WN, Konishi T, Apstein CS (1987) Resistance of neonatal myocardium to injury during normothermic and hypothermic ischemic arrest and reperfusion. Circulation 76 (suppl V): V150-V155
Koenig H, Goldstone A, Luc Y (1982) Testosterone-mediated sexual dimorphism of the rodent heart. Circ Res 50:782–787
Krebs HA, Henseleit K (1932) Untersuchungen über die Harnstoffbildung im Tierkörper. Hoppe-Seylers Z Physiol Chem 210:33–36
Langendorff O (1895) Untersuchungen am überlebenden Säugetierherzen. Pflugers Arch 61:291–332
Moore LG, McMurtry IF, Reeves JT (1978) Effects of sex hormones on cardiovascular and hematologic responses to chronic hypoxia in rats. Proc Soc Exp Biol Med 158:658–664
Nakanishi T, Okuda H, Nakazawa M, Takao A (1985) Effect of acidosis on contractile function in the newborn rabbit heart. Pediatr Res 19:482–488
Nishioka K, Jarmakani JM (1982) Effect of ischemia on mechanical function and high-energy phosphates in rabbit myocardium. Am J Physiol 242:H1077-H1083
Pridjian AK, Levitsky S, Krukenkamp I, Silverman NA, Feinberg H (1987) Developmental changes in reperfusion injury-a comparison of intracellular cation accumulation in the newborn, neonatal and adult heart. J Thorac Cardiovasc Surg 93:428–433
Schaible TF, Scheuer J (1984) Comparison of heart function in male and female rats. Basic Res Cardiol 79:402–412
Scheuer J, Malhotra A, Schaible TF, Capasso J (1987) Effects of gonadectomy and hormonal replacement on rat hearts. Circ Res 61:12–19
Siegmund W, Lepran I, Szekeres L (1980) Effect of pentobarbitone anesthesia, age and sex in the acute phase of myocardial infarction in rats. In: Tardos L, Szekeres L, Papp JG (eds) Pharmacological control of heart and circulation. Akademiai Kiado/Pergamon Press, Budapest Oxford, pp 63–66
Wexler BC, Greenberg BP (1979) Effect of gonadectomy on isoproterenol-induced myocardial infarction. Angiology 30:377–394
Yano Y, Braimbridge MV, Hearse DJ (1987) Protection of the pediatric myocardium: Differential susceptibility to ischemic injury of the neonatal rat heart. J Thorac Cardiovasc Surg 94:887–896
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Avkiran, M., Hearse, D.J. Sex differences in the tolerance of immature rat myocardium to global ischemia. Basic Res Cardiol 83, 618–625 (1988). https://doi.org/10.1007/BF01906956
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DOI: https://doi.org/10.1007/BF01906956