| RESEARCH PAPER
|Year : 1989 | Volume
| Issue : 4 | Page : 111-119
Investigation of ethinyl estradiol induced potentiation of noradrenaline responses in isolated rat vas deferens
JD Bhatt, OD Gulati
1. The effects of acute in vitro exposure of rat isolated vas deferens to ethinyl estradiol (EE; 1.01 x 10-5M) on the contractile responses to various agonists were investigated.
2. EE increased the pD2 values of noradrenaline (NE) and phenylephrine (PE); the pD2 values of methoxamine (MTX), and acetylcholine (ACh) were unaltered.
3. Pretreatment of vas deferens with neuronal uptake blocker, cocaine (1 x 10-5M) and also its denervation abolished the potentiating effect of EE on NA responses.
4. Pretreatment with extraneuronal uptake blocker, normetanephrine (1.2 x 10-5M) or monoamine oxidase (MAO) inhibitor, nialamide (3.35 x 10-5M) or catechol-O-methyl transferase (COMT) inhibitor tropolone (2 x l0-6M) or NE+-K+ ATPase inhibitor, digoxin (3.2 x l0-6GM) did not modify the potentiating effect of EE on NE response.
5, Combined treatment with normetanephrine (1.2 x l0-5M) pargyline (5.2 x l0-6M) and tropolone (2 x 10-6M) did not alter the potentiating effect. However, combined treatment with cocaine (1x 10-5M), normetanephrine (I .2 x 10-5), pargyline (5.2 x 10-5M) and tropolone (2 x 10-6M) abolished the potentiating effect.
6. It is concluded that in rat isolated vas deferens EE, specifically potentiated the contractile responses to certain alpha-adrenoceptor agonists, especially NE. which may be due to its neuronal uptake blocking property.
J D Bhatt
Source of Support: None, Conflict of Interest: None