Background-Sildenafil inhibits phosphodiesterase 5 (PDE5A) to elevate intracellular cGMP and to induce vasodilation.This effect has led to its use for treating erectile dysfunction. Although its influence on rest heart function has appeared minimal, recent animal studies suggest that sildenafil can have potent effects on hearts stimulated by ␤-adrenergic or pressure overloads. We therefore tested whether sildenafil blunts dobutamine-stimulated cardiac function in humans. Methods and Results-Thirty-five healthy volunteers underwent a randomized, double-blind, placebo-controlled study in which cardiac function was assessed in response to dobutamine before and after oral sildenafil (100 mg, nϭ19) or placebo (nϭ16). Echo Doppler and noninvasive blood pressure data yielded load-independent contractility indexes (maximal power index and end-systolic elastance), ejection fraction, and measures of diastolic function. In the initial dobutamine test, systolic and diastolic function improved similarly in both treatment groups (eg, peak power index rose 80Ϯ28% in the placebo group and 82Ϯ31% in the sildenafil group; PϭNS). However, in subjects who then received sildenafil, their second dobutamine response was significantly blunted, with peak power, ejection fraction, and end-systolic elastance changes reduced by 32Ϯ34%, 66Ϯ64%, and 56Ϯ63%, respectively (each PϽ0.001 versus the initial response). This contrasted to the placebo group, which displayed similar functional responses with both dobutamine tests. Sildenafil treatment did not significantly alter diastolic changes induced by dobutamine compared with results with placebo.

Type 1 diabetics have a well-recognised risk of accelerated cardiovascular disease. Even in the absence of clinical signs there are detectable abnormalities of conduit vessel function. Our group has previously reported reversal of endothelial dysfunction in diabetics with pravastatin. In young asymptomatic smokers, taurine supplementation has a beneficial impact on macrovascular function, assessed by FMD, and shows an up-regulation of nitric oxide from monocyte-endothelial cell interactions. We hypothesise that taurine supplementation reverses early endothelial abnormalities in young male type 1 diabetics, as assessed by applanation tonometry, brachial artery ultrasound and laser Doppler fluximetry. Asymptomatic, male diabetics (n=9) were scanned prior to treatment and then randomised in a double-blind cross-over fashion to receive either 2 weeks placebo or taurine. Control patients (n=10) underwent a baseline scan. Assessed diabetics had detectable, statistically significant abnormalities when compared with controls, in both arterial stiffness (augmentation index) and brachial artery reactivity (FMD). Both of these parameters were returned to control levels with 2 weeks taurine supplementation. In conclusion, 2 weeks taurine supplementation reverses early, detectable conduit vessel abnormalities in young male diabetics. This may have important implications in the long-term treatment of diabetic patients and their subsequent progression towards atherosclerotic disease.

Male infantry soldiers (n = 34) were studied before, during, and after a 5-day simulated combat exercise. During the exercise, subjects were rated on their field performance by senior infantry non-commissioned officers. Prior to the exercise, direct measures of body composition and maximal oxygen uptake were obtained. Before and after the exercise the Army Physical Fitness Test and various measures of anaerobic capacity (Wingate and Thorstensson tests) and muscular strength (isometric and isokinetic) were obtained. Results showed no significant decrement in field performance during the exercise. Upper-body anaerobic capacity and strength declined following the exercise, although the results for upper-body strength were not consistent on all measures. Field performance was significantly correlated with measures of upper-body anaerobic capacity and strength. Upper-body strength and anaerobic capacity appear to be important for infantry operations and subject to declines during combat operations.

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