Active vasodilation effects most of the reflex increase in skin blood flow during heat stress by release of acetylcholine and an unknown cotransmitter from cutaneous sympathetic nerves. Among possible cotransmitters are atrial natriuretic peptide(ANP) and vasoactive intestinal peptide(VIP) which are found in efferent nerves innervating cutaneous blood vessels. To examine whether these neuropeptides could be the co-transmitter that effects active vasodilation, we measured plasma ANP and VlP(radioimmunoassay) from superficial forearm veins in normothermia, during hyperthermia, and after recovery from whole body heat stress(water perfused suits). Skin blood flow was simultaneously monitored by laser-Doppler flowmetry(LDF) in each of 5 subjects. Internal temperature and blood pressure(Finapres) were measured. Cutaneous vascular conductance was calculated(CVC=LDF/MAP). During normothermia, plasma levels of ANP and VIP were 57±3 and 16±4pg/ml respectively. During heat stress, ANP rose to 71±4pg/ml (p<0.05), but VIP was not significantly changed (18±7pg/ml, p>0.05). During hyperthermia, CVC rose to an average of 515±102% of normothermic levels(p<0.05). After recovery from heat stress, CVC returned to normothermic levels(p>0.05). ANP also returned to normothermic levels(50±6pg/ml, p>0.05 vs. normo, p<0.05 vs. hyperthermia). VIP remained unchanged(16±4pg/ml, p>0.05). Our finding that ANP increases during heat stress, but that VIP levels do not, suggests ANP could mediate cutaneous active vasodilation.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology