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Biomedical subjects

E Hong

Publications and source records attributed to E Hong.

169 records · Page 10Linked to original sources
PubMedDate not supplied

[The alpha-antiadrenergic properties of spiroxatrine, a ligand of serotonergic 5-HT1A receptors].

The 5-HT1A ligand, spiroxatrine, displays very low affinity for alpha 1-adrenergic binding sites and a relatively high affinity for alpha 2-adrenergic binding sites. Nonetheless, recent functional studies indicate that spiroxatrine is a potent antagonist of the alpha 1-adrenoceptor mediating contraction in the rat isolated aorta. On the basis of the widely studied heterogeneous interaction of drugs with alpha-adrenoceptors in several experimental models, the present study was designed to analyze the alpha-adrenoceptor antagonist properties of spiroxatrine in the pithed rat. Animals were prepared for recording of arterial blood pressure and intravenous (i.v.) administration of drugs. Norepinephrine and the alpha 1- and alpha 2- adrenoceptor agonists methoxamine and clonidine, respectively, elicited pressor responses in a dose-related fashion. Spiroxatrine (1 mg/kg, i.v.) produced a moderate--but significant--rightward displacement of the dose-response curves to all agonists. The present data lead us to suggest that, though spiroxatrine exhibits alpha 1- and alpha 2-adrenoceptor antagonist properties in the pithed rat, its potency does not seem to correlate with that found in rat aorta. The potential involvement of alpha 1-adrenoceptor subtypes is discussed.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

[An analysis of the antihypertensive properties of 3-nitropropionic acid, a compound from plants in the genus Astragalus].

3-Nitropropionic acid (NPA), a compound obtained from Astragalus species, elicited a dose-dependent relaxation of precontracted rabbit aortic rings. The remotion of endothelium or the presence of atropine, propranolol or brompheniramine did not modify the vasodilator effect of NPA but methylene blue clearly inhibited it. On the other hand the acute i.v. administration of NPA in normotensive rats or the chronic oral administration of NPA in renal hypertensive dogs, provoked both a decrease in blood pressure and bradycardia. Finally, NPA elicited negative inotropic and chronotropic effects in guinea pig isolated auricles, which were not blocked by atropine and it inhibited the increase in contractile force and heart rate elicited by isoproterenol. The present results indicate that NPA has vasodilator and antihypertensive properties. The arterial relaxation elicited by NPA was inhibited with methylene blue suggesting that it is a consequence of guanylate cyclase stimulation. The hypotensive effect was independent of the animal species or route of administration used. The bradycardia seen in rats and dogs and the negative chronotropic and inotropic effects observed in isolated auricles suggest that the hypotensive effect of NPA is a mixture of vasodilator and cardiodepressor actions. NPA cardiac effects may be related with inhibition of beta-adrenergic mediated responses.

Animals↗
PubMedDate not supplied

[Evaluation of the toxicity of indorenate on reproduction].

Indorenate (TR3369) a new antihypertensive drug, was examined for effects upon general reproductive performance, for peri-postnatal and embryofetal toxicity in the rat at doses of 0, 10, 20, 40 and 60 mg/kg/day by oral administration. Excluding the 60 mg/kg dose, in the fertility study, any dose produced neither decrement of body weight gain of progenitors, fertility, fetal weight nor survival rate. Retardation of the surface righting, pinnal unfolding or startle response were not observed. On the other hand, 40 and 60 mg/kg significantly increased the number of resorptions. In the peri-postnatal study, doses of 40 and 60 mg/kg incremented the number of dead pups at birth, and the later also affected the survival rate, growing and air righting reflex. Reproductive performance of the F1 offsprings was unimpaired. Indorenate in contrast to serotonin, from which it is a structural derivative, gave no evidence of teratogenicity when administered during the period of organogenesis. It was concluded that the parameters of fetal development were not affected by doses of up to 20 mg/kg, which represents approximately 1200 times the proposed dose for hypertensive patients.

5-Methoxytryptamine↗
PubMedDate not supplied

[Differences between the effects of indorenate and other 5-HT1A agonists on the rabbit aorta].

The aim of this study was to determine if like buspirone, ipsapirone and 8-hydroxy-2(di-N-propylamino)tetralin (8-OH-DPAT), the alpha 1-adrenoceptors are involved in the responses elicited by indorenate in rabbit aorta. Exception made of ipsapirone, all the 5-HT1A agonists above mentioned contracted aortic rings. The contraction elicited by buspirone and 8-OH-DPAT was blocked with prazosin (alpha 1-adrenergic antagonist), whereas the effect of indorenate was unaffected with this blocker but it was inhibited with ritanserin (5-HT2 antagonist). On the other hand, buspirone, ipsapirone and 8-OH-DPAT but not indorenate relaxed arteries precontracted with methoxamine (alpha 1-adrenergic agonist) and none of the agonists relaxed preparations precontracted with acetylcholine or KCl. The results indicate that buspirone and 8-OH-DPAT are partial alpha 1-adrenoceptor agonists since they elicited contractions which are blocked with prazosin and relaxed only rings precontracted with methoxamine. Ipsapirone behaved as an alpha 1-adrenoceptor antagonist since it showed the relaxant but not the contractile effect. Finally, we found no evidence that indorenate has afinity for alpha 1-adrenoceptors. Contraction elicited by this agonist seems to be mediated by 5-HT2 receptors, inasmuch it was blocked with ritanserin.

5-Methoxytryptamine↗