Effects of synthetic leukotriene D-4 on the local regulation of blood flow in human subcutaneous tissue.
Prostaglandin E-1 and E-2 acts as vasodilators partly through inhibition of sympathetic nerves and partly through a direct action on smooth muscle. To elucidate the mechanisms of LTD-4 induced vasodilation, the vascular smooth muscle dependent auto-regulation of blood flow and the sympathetic reflex mechanism of the "vasoconstrictor reflex" was investigated in humans. Blood flow was measured in subcutaneous tissue after injection of 133-Xenon 1) alone, 2) mixed with lidocaine 20 mg/ml for sympathetic blockade, 3) mixed with PGE-2 0.1 ug/ml and 4) mixed with LTD-4 in concentrations of 5 and 20 microM. Blood flow was kept constant during elevation by 20 cm above heart level (preserved autoregulation) except after injection of PGE-2 and LTD-4 20 microM where a significant decrease was observed (defective smooth muscle function). During lowering by 45 cm, a decrease in blood flow by 50% was observed in experiment 1. This response was blocked by lidocaine and PGE-2, partially blocked by LTD-4 20 microM but unaffected by LTD 5 microM. LTD-4 affects vascular smooth muscle function but does not affect sympathetic reflexes in concentrations which does not have a direct smooth muscle action.
D000328:Adult; D000368:Aged; D015232:Dinoprostone; D006801:Humans; D008012:Lidocaine / Q000494:pharmacology; D008875:Middle Aged; D011458:Prostaglandins E / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D013189:SRS-A / Q000494:pharmacology*; D012867:Skin / Q000098:blood supply*
D011458:Prostaglandins E; D013189:SRS-A; D008012:Lidocaine; D015232:Dinoprostone