Histamine H2 Receptor Blockade Augments Blood Pressure Responses to Acute Submaximal Exercise in Males

Histamine is a potent vasodilator that has been found to increase during exercise. We tested the hypothesis that histamine attenuates blood pressure, cardiac output (CO) and vascular resistance responses to short term, submaximal dynamic exercise during H2 receptor blockade. Fourteen healthy men (20-29 yr) were studied. Systolic (SBP), diastolic (DBP) and mean (MAP) arterial blood pressure and heart rate (HR) were assessed at rest and during the last min of 10 min of submaximal cycling exercise (60% of V02peak) in the absence and presence of histamine H2 receptor blockade (ranitidine, 300 mg). Stroke volume (SV) (impedance cardiography) and plasma norepinephrine (NE) were measured and CO, rate x pressure product (RPP) and total peripheral resistance (TPR) were calculated. Plasma levels of histamine were also measured. H2 blockade had no effects on any variables at rest. During exercise, SBP (184± 3 vs. 166±2 mmHg), MAP (121±2 vs. 112±5 mmHg), RPP (25.9±0.8 x 103 vs. 23.5±0.8.0 x 103 mmHg • beats/min) were greater during blocked conditions (PThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author