Ketanserin Modulates Rabbit Foot Cooling in the Presence or Absence of Exogenous Serotonin

摘要

Because hypothermic conditions augment sensitivity to vasoactive amines like serotonin (5-HT) and 5-HT is associated with the etiology of Raynaud's phenomenon, this amine perhaps plays a role in cold-induced vasoconstriction. To determine if 5-HT participated in normal peripheral cooling and if Ketanserin (KET), a 5-HT blocker, modulated such cooling, four groups of New Zealand white rabbits were studied. The femoral artery was cannulated to allow perfusion of a hindlimb. A thermister was implanted in the footpad and rectum. The hindfoot was exposed to a 15 C bath for 30 min, while footpad and rectal temperatures were recorded. The rabbit footpad cooled rapidly when exposed to exogenous 5-HT (group 1). KET treatment in the presence of exogenous 5-HT (group 2) was associated with a significantly reduced cooling rate. KET treatment in the absence of exogenous 5-HT (group 3) was also associated with a significantly elevated limb temperature when compared to controls (group 4). This suggested that endogenous 5-HT participated in limb cooling. Therefore, as noted for Raynaud's disease, 5-HT may also influence peripheral cooling of tissues free of such pathologies. Since Ket treatment did not significantly alter rectal temperature in comparison to controls such treatment with mild cold exposure may have potential in the regulation of peripheral temperature without increasing the risk of hypotherma.