Plasma levels of 5-hydroxytryptamine during sympathetic stimulation and in Raynaud's phenomenon.
1. The involvement of plasma 5-hydroxytryptamine in normal subjects during sympathetic stimulation and in patients with Raynaud's phenomenon was studied. 2. Arterial and venous plasma levels of 5-hydroxytryptamine were measured in normal subjects in a warm room, during reflex sympathetic stimulation by body cooling and during intra-arterial infusions of tyramine. Normal subjects (n = 19) had significantly higher levels of 5-hydroxytryptamine in venous plasma [mean 1.42 (SEM 0.23) ng/ml] than in arterial plasma [0.67 (0.12) ng/ml; P < 0.01]. Body cooling (n = 10) or tyramine infusion (n = 8) did not increase venous levels of 5-hydroxytryptamine despite significant decreases in blood flow and increases in vascular resistance. 3. Venous plasma levels of 5-hydroxytryptamine were also determined in patients with primary Raynaud's phenomenon (n = 12) or secondary Raynaud's phenomenon due to scleroderma (n = 11). Patients with primary or secondary Raynaud's phenomenon did not have significantly higher venous plasma levels of 5-hydroxytryptamine than normal subjects, even during vasospastic attacks (n = 3). 4. It is concluded that either 5-hydroxytryptamine is not involved in sympathetic nerve vasoconstriction or in Raynaud's phenomenon, or 5-hydroxytryptamine released in the microcirculation is largely taken up or metabolized by endothelial cells or platelets.
Coffman
J D
JD
Evans Medical Department of Clinical Research, Boston University Medical Center, University Hospital, MA 02118.
Cohen
R A
RA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003080:Cold Temperature / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011928:Raynaud Disease / Q000097:blood*; D012039:Regional Blood Flow / Q000187:drug effects; D012701:Serotonin / Q000097:blood*; D013268:Stimulation, Chemical; D013564:Sympathetic Nervous System / Q000187:drug effects*; D014439:Tyramine / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects
D012701:Serotonin; D014439:Tyramine