Pulmonary and peripheral vascular factors are important determinants of peak exercise oxygen uptake in patients with heart failure.

Objectives: This study was conducted to determine the relations among exercise capacity and pulmonary, peripheral vascular, cardiac and neurohormonal factors in patients with chronic heart failure.

Background: The mechanisms of exercise intolerance in heart failure have not been fully clarified. Previous studies have indicated that peripheral factors such as regional blood flow may be more closely associated with exercise capacity than cardiac function, whereas the role of pulmonary function has received less attention.

Effects of cardiac transplantation on endothelium-dependent dilation of the peripheral vasculature in congestive heart failure.

Patients with congestive heart failure demonstrate attenuated endothelium-dependent vasodilation of the peripheral vasculature, but there are no data regarding the effect of therapies on this abnormality or whether this abnormality is reversible. This study was performed to address the hypothesis that abnormalities in endothelium-dependent vasodilation in heart failure are improved by heart transplantation. Forearm blood flow responses to the intraarterial administration of a dose range of methacholine, an endothelium-dependent vasodilator, and nitroprusside, an endothelium-independent vasodilator, were examined in 2 separate protocols.

Effects of AMPPNP on the orientation and rotational dynamics of spin-labeled muscle cross-bridges.

We have used electron paramagnetic resonance (EPR) to investigate the orientation, rotational motion, and actin-binding properties of rabbit psoas muscle cross-bridges in the presence of the nonhydrolyzable nucleotide analogue, 5'-adenylylimido-diphosphate (AMPPNP). This analogue is known to decrease muscle tension without affecting its stiffness, suggesting an attached cross-bridge state different from rigor. We spin-labeled the SH1 groups on myosin heads and performed conventional EPR to obtain high-resolution information about the orientational distribution, and saturation transfer EPR to measure microsecond rotational motion.

EPR evidence for nucleotide effects on attached cross-bridges.

We have used electron paramagnetic resonance (EPR) to study the effects of ATP and nucleotide analogs (mainly AMPPNP) on the orientation (measured by conventional EPR) and microsecond rotational dynamics (measured by saturation transfer EPR, STEPR) of spin-labeled myosin heads, both in glycerinated muscle fibers and in solutions of purified S1 and actin. Attachment to actin was determined by stiffness measurements in fibers and by covalent cross-linking in acto-S1. Our goal is to determine whether these nucleotides induce conformations of attached cross-bridges that have head orientations or motions significantly different from rigor.