Various modulators of neurotransmission were examined for selective effects on the non-adrenergic or adrenergic components of neurotransmission in the vas deferens to test the hypothesis that ATP and norepinephrine are secreted from the same vesicles. The ATP receptor antagonist, arylazido aminopropionyl ATP (ANAPP), selectively depressed the non-adrenergic contraction and prazosin selectivity depressed the adrenergic contraction in response to electrical stimulation. These results are consistent with the presence of two neurotransmitters, ATP and norepinephrine, which mediate neurogenic contractions. Prostaglandin E2 inhibited non-adrenergic, but enhanced adrenergic, electrically induced (10 Hz) contractions, presumably via a prejunctional mechanism. The adrenergic component of the neurogenic response was significantly more sensitive to treatment with guanethidine, guanabenz, and 6-hydroxydopamine. These results with a variety of agents are inconsistent with the hypothesis that the neurotransmitters, ATP and norepineprine, are released in tandem from the same neuronal granules.
Bibliographical noteFunding Information:
We thank Robert Marszalek for his expert technical assistance, Mr. Charles Brownley, Jr. for the supply of guanethidine sulfate and Ms. Susan Kurki and Diane Peplinski for the manuscript preparation. This work was supported by Grants RO1 HL19242 and RO1 HL34600 from the National Heart, Lung and Blood Institute.
- Adrenergic neurotransmission
- Purinergic neurotransmission