Hemopressin, a hemoglobin fragment, dilates the rat systemic vascular bed through release of nitric oxide.
The present study was undertaken to investigate the effects of intravenous (i.v.) administration of rat hemopressin (rHP), 30-1000 microg/kg, on systemic arterial pressure (SAP), cardiac output (CO) and systemic vascular resistance (SVR) in the anesthetized rat. Bolus i.v. injections of rHP produced mild decreases in SAP that were dose-dependent. Since CO was not altered, the decreases in SAP reflect reductions in SVR. The systemic vasodilator response to rHP was not subject to tachyphylaxis. The systemic vasodilator response to rHP was abolished by L-nitro-arginine methylester (L-NAME) but was not altered by meclofenamate. In addition, rHP lacked direct contractile and relaxant activity on isolated rat aortic rings (AA) and pulmonary arterial rings (PA). The present data suggest rHP dilates the rat systemic vascular bed through the endogenous release of nitric oxide (NO) independent of the formation of cyclooxygenase products including prostacyclin. It is possible rHP acts as an endogenous vasodilator substance to regulate local blood flow during clinical states of altered red cell turnover, microvascular disease and hemolysis.
Lippton
Howard
H
Pneumosite LLC, Shreveport, LA, USA. hlippton@sport.rr.com
Lin
Bin
B
Gumusel
Bulent
B
Witriol
Norman
N
Wasserman
Anatolio
A
Knight
Martha
M
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D006454:Hemoglobins / Q000494:pharmacology*; D008297:Male; D008469:Meclofenamic Acid / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011651:Pulmonary Artery / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
D006454:Hemoglobins; D010446:Peptide Fragments; D014665:Vasodilator Agents; C473218:hemopressin; D009569:Nitric Oxide; D008469:Meclofenamic Acid; D019001:Nitric Oxide Synthase; D011451:Prostaglandin-Endoperoxide Synthases; D019331:NG-Nitroarginine Methyl Ester