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The most important contributions to the quantification of left ventricular volume in man to date have employed the angiographic technic (1-3). Although stated to be accurate, this method is time-consuming, requires expensive equipment, alters ventricular contraction, is relatively limited in the number of observations that can be made safely, and may present the hazard of myocardial injury. The indicator dilution method for estimation of ventricular volume (4, 5), on the other hand, although more dependent on uniform ventricular mixing and totally unrevealing of ventricular shape, presents the advantages of having little effect on the heart, unlimited repeatability, and simplicity of calculation. This communication reports measurement of left ventricular volume in man by the thermodilution technic (6) under a variety of conditions and the utilization of these data to determine ventricular systolic force and fiber shortening. MethodsThirty-nine patients were studied and classified on the basis of clinical evidence and diagnostic cardiac catheterization. Subjects with mitral regurgitation and significant aortic regurgitation were not included because of the inability to calculate true left ventricular volume in the presence of these defects (7). The following categories were studied:"Normal" left ventricle (22 subjects). This category was divided into groups A and B according to the apparent degree of "normality." Group A comprised seven

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Age-matched male and female Fischer 344 rats were treated with gentamicin, 40 mg/kg of animal body weight per day, for three to 21 days. Renal dysfunction was less severe in females as measured by concentrations of blood urea nitrogen and creatinine and by cortical slice uptake of p-aminohippuric acid and N1-methylnicotinamide chloride. Also, cortical concentrations of gentamicin in females were lower than in males. Neither exogenous testosterone administered to adult females nor castration of prepubertal males changed the pattern of dysfunction. These results show that sex affects susceptibility to aminoglycoside nephrotoxicity by mechanisms that are undefined but that are apparently unrelated to testosterone. The variable of sex needs to be considered in interpreting the results of studies of experimental aminoglycoside nephrotoxicity.

An integrated approach, utilizing cine coronary angiography, the standard 12-lead and post-exercise electrocardiograms, and regional myocardial lactate metabolism, is pre-From the Cardiovascular Research Laboratory and lamin ifsD., isncsavt nuemo Department of Medicine, Peter Bent Brigham Hos-lamine infusion, is necessary to induce myopital and Harvard Medical School, Boston, Massa-cardial production of lactate in the presence chulsetts. of coronary lesions.