Abstract
SRS-A (Slow Reacting Substance of Anaphylaxis) is an important mediator in bronchial asthma and in anaphylactic shock. The structure of SRS-A was recently shown to be leukotriene (LT) C4 and/or LT D4. In present investigation the effect of synthetic LTC4 and LTD4 on isolated perfused rabbit aorta and pulmonary artery strips was studied.
Male rabbits, weighing 2.7-3.9kg, were killed. The pulmonary artery and descending aorta were removed, cut spirally, suspended in a bioassay glass chamber and superfused with Krebs-Henseleit solution at 37°C saturated with oxygen and carbon dioxide (95:5, v/v).
1) LTC4 and LTD4 elicited contractile responses in rabbit aorta and the pulmonary artery strips dose-dependently.
2) LTD4-induced contractile responses in rabbit aorta and pulmonary artery were 5 to 10 times longer than those induced by LTC4.
3) Prostaglandin F2α-, angiotensin II-, epinephrine- and norepinephrine-induced contractile responses in rabbit aorta and pulmonary artery were markedly potentiated with continuous infusion of LTC4 and LTD4. The above results suggest that LTC4 and LTD4 may play an important role in pathological conditions such as bronchial asthma and anaphylactic shock.
