Increased Skin Blood Flow and Enhanced Sensible Heat Loss in Humans afterNicotonic Acid Ingestion

摘要

A series of studies was conducted to characterize thermal and cardiovascularresponses to nicotinic acid (NA) ingestion (5 mg kg-1) in healthy subjects: (a) at rest, seated (Ta = 30aC, RH = 23%) at 0800 h and again between 1800 and 2100 h; (b) at rest and during seated exercise (Ta = 29 deg C, RH = 30%); and (c) during upright exercise when wearing a protective clothing system (Ta = 28 deg C, RH =30%). 2. (a) NA ingestion decreased esophageal (T%) and arterial pressure and increased mean skin temperature (T,k), skin blood flow (skBF), forearm blood flow (FBF), heart rate, and cutaneous vascular conductance (P <0.05) in the morning and evening. In the evening 2/4 subjects experienced substantial hypotension. (b) At rest, peak SkBF and peak FBF were 600% higher in NA than control while T was 0.6%C lower and T%k was 0. 6 deg C higher after NA (P <0.05). During seated exercise, SkBF and FBF were 30% higher and T% was 0.3 deg C lower after NA than control (P <0.05). (c) During upright exercise, NA increased SkBF in subjects clothed in protective clothing. 3. Vascular responsiveness to NA was enhanced in the evening as shown by the increased hypotensive effect of NA in the evening. NA ingestion effectively increased sensible heat flux during rest, seated exercise and upright exercise. However, manipulation of SkBF by NA ingestion should be done cautiously, especially when NA will be used in novel circumstances.