The serotonin 5-Hydroxytryptaphan1A receptor agonist, (+)8-hydroxy-2-(di-n-propylamino)-tetralin, stimulates sympathetic-dependent increases in venous tone during hypovolemic shock.
Adjuvant treatment of hypovolemic shock with vasoconstrictors is controversial due to their propensity to raise arterial resistance and exacerbate ischemia. A more advantageous therapeutic approach would use agents that also promote venoconstriction to augment perfusion pressure through increased venous return. Recent studies indicate that 5-hydroxytryptophan (5-HT)(1A) receptor agonists increase blood pressure by stimulating sympathetic drive when administered after acute hypotensive hemorrhage. Given that venous tone is highly dependent upon sympathetic activation of alpha(2)-adrenergic receptors, we hypothesized that the 5-HT(1A) receptor agonist, (+)8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT), would increase venous tone in rats subject to hypovolemic shock through sympathetic activation of alpha(2)-adrenergic receptors. Systemic administration of 8-OH-DPAT produced a sustained rise in blood pressure (+44 +/- 3 mm Hg 35 min after injection, P < 0.01 versus saline) and mean circulatory filling pressure (+4.2 +/- 0.7 mm Hg, P < 0.01 versus saline) in conscious rats subjected to hypovolemic shock. An equipressor infusion of epinephrine failed to influence mean circulatory filling pressure (MCFP). Ganglionic blockade, alpha(1)-, or peripheral alpha(2)-adrenergic receptor blockade prevented the rise in MCFP observed with 8-OH-DPAT, but only alpha(1)-adrenergic receptor blockade diminished the pressor effect of the drug (P < 0.01). 8-OH-DPAT raises blood pressure in rats in hypovolemic shock through both direct vascular activation and sympathetic activation of alpha(1)-adrenergic receptors. The sympathoexcitatory effect of 8-OH-DPAT contributes to elevated venous tone through concurrent activation of both alpha(1)- and alpha(2)-adrenergic receptors. The data suggest that 5-HT(1A) receptor agonists may provide an advantageous alternative to currently therapeutic interventions used to raise perfusion pressure in hypovolemic shock.
Tiniakov
Ruslan
R
Department of Pharmacology, 2160 South First Avenue, Maywood, IL 60153, USA. kscrogi@lumc.edu
Scrogin
Karie E
KE
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D002496:Central Venous Pressure / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D011807:Quinolizines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D012769:Shock / Q000188:drug therapy* / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology
D011807:Quinolizines; D017366:Serotonin Receptor Agonists; C055732:vatinoxan; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D011224:Prazosin