Effects of forearm bier block with bretylium on the hemodynamic and metabolic responses to handgrip

Sections of 1 Cardiology, 2 Biostatistics, and 3 Anesthesiology and 4 Department of Radiology, Center for Nuclear Magnetic Resonance Research, The Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey 17033; 5 Lebanon Veterans Affairs Medical Center, Lebanon, Pennsylvania 17042; and 6 School of Kinesiology, University of Western Ontario, London, Ontario, Canada N2L 3G1 We tested the hypothesis that a reduction in sympathetic tone to exercising forearm muscle would increase blood flow, reduce muscle acidosis, and attenuate reflex responses. Subjects performed a progressive, four-stage rhythmic handgrip protocol before and after forearm bier block with bretylium as forearm blood flow (Doppler) and metabolic (venous effluent metabolite concentration and 31 P-NMR indexes) and autonomic reflex responses (heart rate, blood pressure, and sympathetic nerve traffic) were measured. Bretylium inhibits the release of norepinephrine at the neurovascular junction. Bier block increased blood flow as well as oxygen consumption in the exercising forearm ( P