Abstract
Pooled, isolated rat vasa deferentia were incubated with 100 ng/ml of (-)-or (+)-norepinephrine-14C (NE-14C) for 10, 30 or 60 minutes or with 10 ng/ml of (-)-or (+)-NE-14C for 60 minutes. Incubated tissues were fractionated by differential centrifugation yielding a 9,000 x g "coarse" pellet, a 105,000 x g "microsomal" pellet and a supernatant fraction. After incubation with 100 ng/ml, no stereoselectivity was apparent in the whole tissue; however, the microsomal fraction demonstrated a preference for (-)-NE-14C at the 30- and 60-minute incubation periods. The subcellular distribution pattern of exogenous NE-14C was quantitatively dissimilar to the distribution pattern of endogenous NE. The effect of various agents and procedures on the accumulation of NE-14C isomers by whole tissue were studied at the 60-minute incubation period with 100 ng/ml. Inhibition of monoamine oxidase enhanced the accumulation of both isomers; however, enhancement of (-)-NE-14C was greater than (+)-NE-14C resulting in a clear stereoselective preference for the (-)-isomer. Vasa deferentia obtained from reserprine-pretreated animals demonstrated an apparent impairment of accumulation and a stereoselective reversal. The combination of reserpine-pretreatment plus inhibition of monoamine oxidase reversed the effect of reserpine-pretreatment, i.e., accumulation was returned to control levels and no stereoselectivity was evident. Reserpine was shown to impair the accumulation of NE-14C isomers by the microsomal fraction. Cocaine, 6-hydroxydopamine and cold storage all impaired the accumulation of both isomers. In addition to the effect of various agents and procedures on prejunctional stereoselectivity, we determined the influence of various agents and procedures on postjunctional stereoselectivity utilizing the isomeric-activity-difference of NE as a tool. In the presence of cocaine, inhibition of both monoamine oxidase and catechol-O-methyl transferase and pretreatment with α-chymotrypsin failed to alter the isomeric-activity-difference. Denervation and cold storage of vasa deferentia resulted in isomeric-activity-differences that were not significantly different from those obtained in normal vasa deferentia in the presence of cocaine. On the basis of similarity of differences, it is suggested that the alpha adrenergic receptor is unaltered by these procedures.
Footnotes
- Received May 13, 1971.
- Accepted March 25, 1972.
- © 1972, by The Williams & Wilkins Company
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