POTASSIUM CHLORIDE-INDUCED AND NOREPINEPHRINE-INDUCED CONTRACTILE RESPONSES IN RABBIT PULMONARY BLOOD-VESSELS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 224  (3) , 572-578
Abstract
Responses to KCl and norepinephrine (NE) were examined with ring segments of the right extrapulmonary artery, intrapulmonary artery and intrapulmonary vein isolated from rabbit lung. From concentration-response curves to KCl, optimal applied loads were 5 g for right extrapulmonary artery and intrapulmonary artery and 500 mg for intrapulmonary vein. Both individual and cumulative concentration-response curves to KCl and NE were performed. All gave reproducible results; however, tissues were more sensitive to cumulative addition of either contractile agent. Of 3 successive cumulative NE concentration-response curves, 2nd and 3rd curves were most reproducible in relation to both sensitivity to NE and maximal force development. Cumulative NE concentration-response curves also exhibited a triphasic pattern, consisting of an initial contractile response (10-10-10-6 M NE) followed by relaxation or reversal of contractile force development (10-6-10-4 M NE), then a 2nd contractile response at concentrations of NE > 10-4 M. This response pattern was most prominent in intrapulmonary vessels and was absent in rabbit aorta.