Related Experiment Videos
Dual vasoactive effects of tolazoline on rabbit pulmonary arteries
Objectives:
To determine the vasoactive effects of tolazoline on isolated rabbit pulmonary arteries.
Design:
Prospective, in vitro, randomized, controlled trial.
Setting:
Experimental laboratory in a university-affiliated hospital.
Participants:
New Zealand White Rabbits.
Interventions:
The pulmonary artery rings were obtained via thoracotomy. Their vasoactive responses were assessed in the presence and absence of intact endothelium and with or without precontraction by norepinephrine (NE, 3 x 10(-6) M) or potassium chloride (KCl, 3 x 10(-2) M). Using a tissue bath preparation, cumulative concentration response curves of tolazoline were obtained at different concentrations (10(-9) to 10(-4) M) after a period of stabilization.
Measurements And Main Results:
Tolazoline caused vasoconstriction of isolated pulmonary arteries without any pretreatment. The magnitude of the constriction was dose related and reached 300 g/g wet tissue at a concentration of 10(-4) M. On KCl-precontracted pulmonary arteries, tolazoline caused significant dose-related vasoconstriction. On the NE-precontracted vessel rings, it elicited significant dose-dependent vasodilation up to 60% relaxation at 10(-5) M. All the above effects were endothelium independent.
Conclusions:
Tolazoline has dual endothelium-independent vasoactive effects, causing vasoconstriction on isolated rabbit pulmonary arteries, either untreated or precontracted with KCl, and vasodilation on those precontracted with NE. Tolazoline may act as a competitive alpha-adrenoceptor blocking agent.