Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:014352 (REC)
 355 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The alpha 1-adrenoceptor population mediating contraction of caudal artery of rat has been characterized by using quantitative receptor pharmacology. 2. Cumulative concentration-effect (E/[A]) curves to noradrenaline (NA) yielded a p[A]50 of 5.56 +/- 0.05 (n = 16). Prazosin caused concentration-dependent, parallel, dextral shifts of E/[A] curves to NA yielding a pKb of 8.9 (Schild regression slope = 1.0). RS-17053 (N-[2-(2-cyclopropyl methoxy phenoxy) ethyl]-5-chloro-alpha, alpha-dimethyl-1H-indole- 3-ethanamine hydrochloride; 10-100 nM), a selective alpha 1 A-adrenoceptor antagonist, produced non-parallel, biphasic, dextral shifts of E/[A] curves to NA, suggesting the involvement of more than one alpha 1-adrenoceptor subtype. Analysis of the high affinity component yielded an apparent pA2 value of 9.2 +/- 0.3. 3. A-61603, a selective agonist at alpha 1A adrenoceptors behaved as a full agonist relative to NA and yielded monophasic E/[A] curves with a p[A50] of 7.59 +/- 0.04 (n = 15). Pretreatment of tissues with chloroethylclonidine (CEC; 100 microM for 20 min, followed by 40 min washout), which preferentially alkylates alpha 1B- and alpha 1D-adrenoceptors, did not alter E/[A] curves to A-61603. Prazosin (3-300 nM) caused concentration-dependent, parallel, dextral shifts of E/[A] curves to A-61603 yielding a pA2 estimate of 9.2 +/- 0.2. 4. Experiments with alpha 1-adrenoceptor antagonists of varying subtype selectivities (RS-17053, SNAP 5089, tamsulosin, 5-methylurapidil, BMY 7378, HV 723 and REC 15/2739) revealed parallel dextral shifts of E/[A] curves to A-61603. Schild regression analyses yielded pA2 estimates of 9.2, 9.3, 11.2, 9.0, 6.3, 8.7 and 10.0 for RS-17053, SNAP 5089, tamsulosin, 5-methylurapidil, BMY 7378, HV 723 and REC 15/2739, respectively, although deviations from unit slope (possibly reflecting a secondary involvement of another alpha 1-adrenoceptor) hindered estimations of pKb for some antagonists. The antagonist affinity profile obtained reflects best that described for the alpha 1A-adrenoceptor. 5. In conclusion, caudal artery of rat contracts in response to NA via activation of at least two alpha 1-adrenoceptor subtypes. One of these subtypes displays the pharmacology of the alpha 1A-adrenoceptor, while the other remains to be defined. Use of the novel selective agonist, A-61603, allows for limited pharmacological isolation of the alpha 1A-adrenoceptor permitting characterization of the properties of selective antagonists.
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PMID:Pharmacological characterization of an alpha 1A-adrenoceptor mediating contractile responses to noradrenaline in isolated caudal artery of rat. 913 87

Vascular and non-vascular smooth muscle within the vagina mediate important physiological changes during sexual arousal in women. In this study, we have characterized alpha-adrenergic receptors (AR) in rabbit vagina by assessment of radioligand binding, contractility of isolated tissue strips and genital hemodynamics. [3H]Prazosin and [3H]RX821002 (alpha-1 and alpha-2 AR selective antagonists) bound to rabbit vaginal membrane preparations with high affinity and limited capacity. Competition binding assays using both non-selective and subtype selective ligands for AR (phentolamine, prazosin, delequamine, rauwolscine and UK14304) further confirmed the presence of alpha-1 and alpha-2 AR in vaginal tissue. In organ bath preparations of vaginal tissue strips, norepinephrine-induced contraction was attenuated by alpha-1 and alpha-2 AR antagonists (prazosin, tamsulosin, delequamine and phentolamine). In anesthetized rabbits, intravaginal injection of the alpha-1 AR selective antagonist REC 15/2615 (50 and 100 microg/kg) caused a 2 to 3-fold increase in genital tissue oxyhemoglobin (OHb) concentration. Similar increases in tissue OHb were observed with intravaginal injection of phentolamine (500 microg/kg) or a tri-mixture of vasodilators (PGE1, papaverine, phentolamine). REC 15/2615, phentolamine or the tri-mixture also enhanced the amplitude and/or duration of change in genital tissue OHb after pelvic nerve stimulation. Thus, vaginal tissue expresses functional alpha-1 and alpha-2 AR, which modulate vaginal smooth muscle contractility and genital engorgement.
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PMID:Biochemical and functional characterization of alpha-adrenergic receptors in the rabbit vagina. 1237 71