Correlation between mRNA levels and functional role of α₁-adrenoceptor subtypes in arteries: evidence of α_1L as a functional isoform of the α_1A-adrenoceptor

Abstract

The mRNA levels for the three alpha1-adrenoceptor subtypes, alpha1A, alpha1B, and alpha1D, were quantified by real-time RT-PCR in arteries from Wistar rats. The alpha1D-adrenoceptor was prominent in both aorta (79.0%) and mesenteric artery (68.7%), alpha1A predominated in tail (61.7%) and small mesenteric artery (73.3%), and both alpha1A- and alpha1D-subtypes were expressed at similar levels in iliac artery. The mRNA levels of the alpha1B-subtype were a minority in all vessels (1.7-11.1%). Concentration-response curves of contraction in response to phenylephrine or relaxation in response to alpha1-adrenoceptor antagonists on maximal sustained contraction induced by phenylephrine were constructed from control vessels and vessels pretreated with 100 micromol/l chloroethylclonidine (CEC) for 30 min. The significant decrease in the phenylephrine potency observed after CEC treatment together with the inhibitory potency displayed by 8-{2-[4-(2-methoxyphenyl)-1-piperazinyl]-8-azaspiro (4,5) decane-7-dionedihydrochloride} (BMY-7378, an alpha1D-adrenoceptor antagonist) confirm the relevant role of alpha1D-adrenoceptors in aorta and iliac and proximal mesenteric arteries. The potency of 5-methylurapidil (an alpha1A-adrenoceptor antagonist) and the changes in the potency of both BMY-7378 and 5-methylurapidil after CEC treatment provided evidence of a mixed population of alpha1A- and alpha1D-adrenoceptors in iliac and distal mesenteric arteries. The low potency of prazosin (pIC50 < 9) as well as the high 5-methylurapidil potency in tail and small mesenteric arteries suggest the main role of alpha1A/alpha1L-adrenoceptors with minor participation of the alpha1D-subtype. The mRNA levels and CEC treatment corroborated this pattern and confirmed that the alpha1L-adrenoceptor could be a functional isoform of the alpha1A-subtype.

MicroRNAs-10a and -10b Contribute to Retinoic Acid-induced Differentiation of Neuroblastoma Cells and Target the Alternative Splicing Regulatory Factor SFRS1 (SF2/ASF)

“…Expression values were calculated using the comparative Ct method, and U6 snRNA was used as an endogenous control. For quantitative real-time PCR of mRNAs, 1 g of total RNA was reverse-transcribed using oligo(dT) 16 and Moloney murine leukemia virus reverse transcriptase as described (36). 1 l of a 10-fold cDNA dilution was subjected to SYBR Green or TaqMan gene expression assays (Applied Biosystems) according to the manufacturer's instructions.…”

Different β‐adrenoceptor subtypes coupling to cAMP or NO/cGMP pathways: implications in the relaxant response of rat conductance and resistance vessels

“…The total RNA from frozen MRA, aorta and SMCs isolated from aorta was obtained and the RT reaction was performed as described previously (Martí et al, 2005). The mRNAs encoding the three Adrb, Nos3 and Gapdh as an internal standard were quantified by TaqMan RT-PCR in a Gene-Amp 5700 sequence-detection system (Applied Biosystems, Foster City, CA, USA).…”

“…Aorta (4 mm) and MRA (2 mm) rings were set-up in an isometric organ bath or a wire myograph (model 610 M, J.P. Trading, Denmark) respectively, filled with Krebs solution at 37°C and gassed with 95% O2 and 5% CO2 as previously described (Martí et al, 2005). An initial load of 1 g was applied to the aorta, while the internal diameter of MRA was set to a tension equivalent to 0.9 times the estimated diameter at 100 mmHg effective transmural pressure (l100 = 90-180 mm) according to the standard procedure of Mulvany and Halpern (1977).…”

Pharmacological Properties of 2-((R-5-Chloro-4-methoxymethylindan-1-yl)-1H-imidazole (PF-3774076), a Novel and Selective α1A-Adrenergic Partial Agonist, in in Vitro and in Vivo Models of Urethral Function

“…As a preclinical species, cardiovascular data from the dog show good concordance with humans (Olson et al, 2000) and taken together with other literature it is questionable whether urethral efficacy can be separated from cardiovascular liability with this mechanism. Although ␣1 B -and ␣1 D -receptors are responsible for contraction of vasculature (e.g., Chalothorn et al, 2003), ␣1 A -receptors are present throughout the vasculature in various species (Piascik et al, 1991;Martí et al, 2005). Centrally, ␣1-receptors are expressed in many areas associated with cardiovascular control (Day et al, 1997;Tsukamoto et al, 2002;Zhang and Mifflin, 2007), although specificity for ␣1 A has not always been demonstrated.…”