TY - JOUR T1 - Calcium antagonist activity of methadone, l-acetylmethadol and l-pentazocine in the rat aortic strip. JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 646 LP - 653 VL - 202 IS - 3 AU - C H Lee AU - B A Berkowitz Y1 - 1977/09/01 UR - http://jpet.aspetjournals.org/content/202/3/646.abstract N2 - These studies described physiologic evidence that methadone and related compounds can function as calcium antagonists. Methadone (1 X 10(-5)-1 X 10(-4) M) inhibited the contraction of the isolated rat aortic strip preparation produced by potassium chloride, norepinephrine, l-pentazocine or morphine. Methadone was most effective in diminishing aortic contractions which were highly dependent on the concentration of extracellular calcium. The d- and l-isomers of methadone were equipotent inhibitors of aortic contraction. l-Acetylmethadol (1 X 10(-6)-1 X 10(-5) M) was a potent inhibitor of vascular contraction. l-Pentazocine inhibited its own ability to contract the aorta as the dose was raised 3 X 10(-5) M. The inhibition of aortic contraction produced by methadone, l-acetylmethadol and l-pentazocine was overcome by raising the concentration of calcium in the tissue baths. The inhibition of contraction and the apparent calcium-antagonist activity of these drugs best correlates with their lipid solubility. Since calcium is a critical regulator of cellular function, the calcium-antagonist action of methadone and l-acetylmethadol may prove to be important in mediating some of their pharmacologic and toxicologic effects. ER -