Increased density of α-adrenoceptors in vas deferens of spontaneously hypertensive rats (SHR), indicated by functional and receptor binding studies

Caricati‐Neto, Afonso; Sette, Mario; Jurkiewicz, Aron

doi:10.1016/0014-2999(92)90146-u

Cited by 16 publications

(14 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The sensitivity of the α-adrenoceptor in the venom gland of Bothrops jararaca is lower than the value we reported for the α-adrenoceptor in the aorta of this snake , suggesting that this snake expresses different subtypes of α-adrenoceptors. The low sensitivity found for the α-adrenoceptor of the venom gland is similar to those found in rat vas deferens circular muscle or spleen (Caricati-Neto et al, 1992;Buckner et al, 1996).…”

Section: Discussionsupporting

confidence: 75%

Stimulation of the α-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca

Kerchove

Carneiro

Markus

et al. 2004

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

Section: Discussionsupporting

confidence: 75%

Stimulation of the α-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca

Kerchove

Carneiro

Markus

et al. 2004

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Receptor binding studies using [ 3 H]WB-4101 demonstrated an increase in the density of α 1 -adrenoceptors in the vas deferens of SHR (Caricati-Neto et al 1992) that could account for the greater reactivity to noradrenaline observed by these and other authors. In previous experiments, the use of different antagonists to displace [ 3 H]prazosin binding showed the existence of a heterogenous dis-…”

Section: Introductionmentioning

confidence: 86%

“…Several studies indicate that tissues other than non-vascular smooth muscle tissues from SHR, such as stomach (Altman et al 1977) or vas deferens, also display a different reactivity to noradrenaline when compared to tissues from normotensive Wistar rats. An increase (Caufield et al 1977;Caricati-Neto et al 1992), no modification (Corbett et al 1980;Sakai et al 1984), or a reduction (Docherty and Warnock 1985) in postjunctional α 1 -adrenoceptor-mediated responses have been reported for the rat vas deferens from SHR when compared with vas deferens from normotensive Wistar or Wistar Kyoto rats (WKY). One of the reasons that may explain the functional differences observed between studies on rat vas deferens could be the lack of controlled experimental conditions, such as those described by Furchgott (1972), that would enable an accurate evaluation of the responses elicited by α 1 -adrenoceptor agonists in rat vas deferens from both SHR and WKY animals to be made.…”

Section: Introductionmentioning

confidence: 99%

Use of the operational model of agonism and [3H]prazosin binding to assess altered responsiveness of α1-adrenoceptors in the vas deferens of spontaneously hypertensive rat

Vivas

Giraldo

Tabernero

et al. 1997

Naunyn-Schmiedeberg's Arch Pharmacol

View full text Add to dashboard Cite

Changes in functional responsiveness to alpha1-adrenoceptor activation with noradrenaline and in [3H]prazosin binding in the epididymal portion of vas deferens from normotensive Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were investigated. The operational model fitting and the nested hyperbolic method were used to analyze the effects of irreversible receptor alkylation by phenoxybenzamine (0.1 microM) on the alpha1-adrenoceptor mediated contractile responses to noradrenaline of vasa deferentia from SHR and WKY rats. Saturation isotherms for [3H]prazosin revealed a significant increase (P < 0.05) in the Bmax in SHR vas deferens (145 +/- 19 fmol/mg protein) compared with vas deferens from normotensive controls (75 +/- 12 fmol/mg protein) without changes in the K(D). No differences in the proportion of high and low affinity binding sites for WB-4101 and 5-methylurapidil were observed. The maximum contractile response, alpha, (P < 0.001) and the pEC50 (P < 0.05) values for noradrenaline were greater for SHR than for WKY rat tissues. The apparent affinity (pK(A)) determined by the nested hyperbolic method and by the operational model of agonism was found to be similar in the two strains. In agreement with relative pEC50, the efficacy (tau) value for SHR was greater than for WKY rats. However, the difference in the tau estimates did not reach statistical significance. In summary, in the epididymal portion of SHR vas deferens, the increased maximum contractile response to noradrenaline is due to an increase of Em. Taken together, the tau values and the results from binding experiments lead to the assumption that the transducer constant K(E) must be greater in SHR than in WKY rats, suggesting a deterioration in the transduction of the stimulus provided by the agonist in hypertensive animals.

show abstract

“…It is known that NA-induced contractions are associated with an increase in cytosolic cal cium concentration through α 1 -adrenoceptors [35]. In earlier studies, maximal effects induced by NA were significantly greater in SHR, without changes in affinity [14]. Katsuragi et al [17] reported that the endogenous NA content in VD and electrically evoked release of NA from tissues was identical in SHR and WKY rats.…”

Section: αβ-Meatp-induced Contractile Responses Of Vdmentioning

confidence: 94%

“…In previous studies carried out in spontaneously hypertensive rats (SHR), VD displayed an altered postjunctional functionality of α 1 -adrenoceptors [14,15]. Similarly, an increased purinergic contribution to the co-transmission process has been described in nervemediated contractions by electrical field stimulation (EFS) recorded in isolated caudal arteries of SHR [10,16,17].…”

mentioning

confidence: 91%

Purinergic contraction of the rat vas deferens in L-NAME-induced hypertension: effect of sildenafil

Gür¹,

Sikka²,

Knight³

et al. 2010

Asian J Androl

View full text Add to dashboard Cite

Hypertension (HTN) is a risk factor for erectile dysfunction, but its effect on vas deferens (VD) contractility and the ejaculatory response has not been delineated. NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, was used for induction of nitric oxide (NO)-deficient HTN. Our aim was to evaluate the effects of L-NAME-induced HTN on rat VD contractility and to determine whether sildenafil affects VD contractility. A total of 36 male rats were divided into (1) control, (2) L-NAME-HTN, (3) sildenafil treated L-NAME-HTN groups. Group 2 was treated with L-NAME (40 mg kg -1 per day) in drinking water for 4 weeks. Group 3 received sildenafil (1.5 mg kg -1 per day, by oral gavage) concomitantly with L-NAME. The prostatic portion of the VD was subjected to electrical field stimulation (EFS, 1-20 Hz), and the P2X 1 agonist α,β-methylene ATP (α,β-meATP, 100 μmol L -1 -1 μmol L -1 ) and the α1-adrenoceptor agonist phenylephrine (Phe, 100 μmol L -1 -1 mmol L -1 ) were used to construct concentration-response curves. These experiments were repeated in the presence of P2X receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS, 30 μmol L -1 ). VD contractions in response to EFS, α,β-meATP and Phe were significantly enhanced by L-NAME. Sildenafil treatment in the L-NAME group improved the contractile response of VD to EFS (20 Hz). In the presence of PPADS, the enhanced contractile response of VD to EFS and α,β-meATP in hypertensive rats was reversed. In the rat model of chronic NO depletion, the purinergic and adrenergic components and EFS affect VD contractility. The VD contractile response may be mediated more by the purinergic system than the adrenergic system, and sildenafil may alter the ejaculatory response in men with PE.

show abstract

Increased density of α-adrenoceptors in vas deferens of spontaneously hypertensive rats (SHR), indicated by functional and receptor binding studies

Cited by 16 publications

References 32 publications

Stimulation of the α-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca

Stimulation of the α-adrenoceptor triggers the venom production cycle in the venom gland of Bothrops jararaca

Use of the operational model of agonism and [3H]prazosin binding to assess altered responsiveness of α1-adrenoceptors in the vas deferens of spontaneously hypertensive rat

Purinergic contraction of the rat vas deferens in L-NAME-induced hypertension: effect of sildenafil

Contact Info

Product

Resources

About