Effects of atropine and L-NAME on cutaneous blood flow during body heating in humans.
We sought to investigate further the roles of sweating, ACh spillover, and nitric oxide (NO) in the neurally mediated cutaneous vasodilation during body heating in humans. Six subjects were heated with a water-perfused suit while cutaneous blood flow was measured with a laser-Doppler flowmeter. After a rise in core temperature (1. 0 +/- 0.1 degrees C) and the establishment of cutaneous vasodilation, atropine and subsequently the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) were given to the forearm via a brachial artery catheter. After atropine infusion, cutaneous vascular conductance (CVC) remained constant in five of six subjects, whereas L-NAME administration blunted the rise in CVC in three of six subjects. A subsequent set of studies using intradermal microdialysis probes to selectively deliver drugs into forearm skin confirmed that atropine did not affect CVC. However, perfusion of L-NAME resulted in a significant decrease in CVC (37 +/- 4%, P < 0.05). The results indicate that neither sweating nor NO release via muscarinic receptor activation is essential to sustain cutaneous dilation during heating in humans.
Shastry
S
S
Department of Physiology and Biophysics, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
Minson
C T
CT
Wilson
S A
SA
Dietz
N M
NM
Joyner
M J
MJ
D000328:Adult; D001285:Atropine / Q000494:pharmacology*; D001831:Body Temperature / Q000502:physiology*; D001916:Brachial Artery / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007260:Infusion Pumps; D008297:Male; D017551:Microdialysis; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D010276:Parasympatholytics / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D012867:Skin / Q000098:blood supply*; D012879:Skin Physiological Phenomena / Q000187:drug effects; D013546:Sweating / Q000502:physiology; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects
D004791:Enzyme Inhibitors; D010276:Parasympatholytics; D001285:Atropine; D019331:NG-Nitroarginine Methyl Ester