DRUG-INDUCED VASODILATION - THE EFFECTS OF SODIUM-NITROPRUSSIDE, HYDRALAZINE, AND CROMAKALIN ON THE RABBIT CAROTID-ARTERY - IN-VITRO AND IN-VIVO STUDY

Citation
A. Gurlek et al., DRUG-INDUCED VASODILATION - THE EFFECTS OF SODIUM-NITROPRUSSIDE, HYDRALAZINE, AND CROMAKALIN ON THE RABBIT CAROTID-ARTERY - IN-VITRO AND IN-VIVO STUDY, Journal of reconstructive microsurgery, 13(6), 1997, pp. 415-421
Citations number
24
Categorie Soggetti
Surgery
ISSN journal
0743684X
Volume
13
Issue
6
Year of publication
1997
Pages
415 - 421
Database
ISI
SICI code
0743-684X(1997)13:6<415:DV-TEO>2.0.ZU;2-7
Abstract
Extreme arterial and venous constrictions are common problems in micro vascular surgery, often leading to tissue injury and flap failure. The ideal pharmacologic tool to counteract. ischemia should exert its act ion both locally and distally in the microcirculation of the flap, In this study, the vascular properties of sodium nitroprusside, hydralazi ne, and cromakalin were evaluated and compared in in vitro and in viva models in the rabbit carotid artery. In the in vitro study, 20 rings from the rabbit carotid artery were bathed in Krebs-Ringers solution, stretched progressively to an optimal tension of 3.7 to 4.2 gm, and th eir isometric contractile activity was measured. The specimens were pr econtracted with norepinephrine (1 mu M) and a dose-response curve was established by adding cumulatively either sodium nitroprusside (n = 7 ), cromokalin (n = 7), or hydralazine (n = 7) at increasing concentrat ions. In the in vivo study, microvascular anastomoses were performed b ilaterally in the rabbit carotid artery in 19 animals using 9-0 nylon suture and standard microsurgical techniques. In each animal, one side was treated with heparinized sodium chloride, and served as control. The other side was treated blindly with the topical application of 1 m l of either sodium nitroprusside (10 mg/ml, n = 5), hydralazine (20 mg /ml, n = 5), or cromakalin (25 mg/ml, n = 4), during and after the ana stomoses. Blood-flow changes in the vessels were continuously monitore d with the transonic Doppler applied to both carotid arteries for 60 m in after the procedure. Sodium nitroprusside and cromakalin elicited a concentration-dependent relaxation of norepinephrine-precontracted ca rotid artery rings in vitro. Sodium nitroprusside was significantly mo re effective than cromakalin in inducing relaxation. Hydralazine elici ted a biphasic response, with low concentrations (1.5 x 10(-5) to 1.5 x 10(-3) M) potentiating the norepinephrine-induced contraction, and h igh concentrations relieving this contraction. Microsurgical anastomos is in the rabbit carotid artery-produced a significant decrease of blo od flow through the vessel as measured by the transonic Doppler for 30 min. Topical application of heparinized saline did not significantly change the blood flow after the microvascular anastomosis. Topical app lication of sodium nitroprusside and cromakalin significantly increase d the blood flow in the vessel after the anastomosis; however, the top ical hydralazine did not significantly alter blood flow, but demonstra ted a trend toward increased flow values. The data support the conclus ion that sodium nitroprusside and cromakalin could be used to relieve vascular constriction. It is suggested that further studies on the cli nical use of these drugs in microsurgery is warranted.