Localization and characterization of two propranolol resistant (−) [125I]cyanopindolol binding sites in rat skeletal muscle

Ligand binding properties of putative β3‐adrenoceptors compared in brown adipose tissue and in skeletal muscle membranes

“…By using the highly sensitive technique of autoradiography. Molenaar et al (1991) found that ['25f1-ICYP labels a small number of 5-HT receptors in soleus muscle; however, these workers were unable to detect labelled 5-HT binding sites in competitive ligand binding experiments (R.J. Summers, personal communication) and the results of the present study confirm this latter observation. The present observation that BAT hosts a mixed population of Plor 2-adrenoceptors also agrees with a number of earlier findings (for review see Arch, 1989), and the proportion of these two sites observed in the present study is in particularly close agreement with PKD Brown adipose tissue Figure 3 The relationship between atypical ['1251]binding sites in soleus muscle and brown adipose pK (negative log dissociation constant) were obt compounds from competitive ligand binding expei the proportion of 59% Pland 41%P2-adrenc ed by Rothwell et al (1985).…”

“…The present observation that BAT hosts a mixed population of Plor 2-adrenoceptors also agrees with a number of earlier findings (for review see Arch, 1989), and the proportion of these two sites observed in the present study is in particularly close agreement with PKD Brown adipose tissue Figure 3 The relationship between atypical ['1251]binding sites in soleus muscle and brown adipose pK (negative log dissociation constant) were obt compounds from competitive ligand binding expei the proportion of 59% Pland 41%P2-adrenc ed by Rothwell et al (1985). Previous reports of atypical binding sites b rat skeletal muscle are relatively few (MooI 1991;Kim et al, 1991;Roberts et al, 1991) when Molenaar et al (1991) reported the lo propranolol-resistant [251I]-ICYP binding site cle, they found certain discrepancies between t graphy data and pA2 values reported in the lii atypical receptor in rat adipocytes. This prom et at.…”

Characterization of β‐adrenoceptor mediated smooth muscle relaxation and the detection of mRNA for β1‐, β2‐ and β3‐adrenoceptors in rat ileum

“…The reason for this difference is not known. Low stereoselectivity was observed for isomers of alprenolol competing for (−)‐[ 125 I]‐CYP binding in rat skeletal muscle ( Molenaar et al ., 1991 ; Roberts et al ., 1993 ; Sillence et al ., 1993 ) and brown adipose tissue membranes ( Sillence et al ., 1993 ). It is interesting to note that much higher stereoselectivity has been observed for agonists at atypical β‐ARs, particularly the isomers of ISO which display 25 fold separation in rat small intestine ( Van der Vliet et al ., 1990 ) and 31 fold separation at the cloned human β 3 ‐AR expressed in CHO cells ( Emorine et al ., 1989 ).…”

Effects of the enantiomers of R,S‐salbutamol on incompletely fused tetanic contractions of slow‐ and fast‐twitch skeletal muscles of the guinea‐pig

“…However, in recent years it has become apparent that in addition to the classical β 1 ‐ and β 2 ‐adrenoceptor there also exists atypical β‐adrenoceptors, such as the β 3 ‐ (Arch & Kaumann, 1993) and β 4 ‐adrenoceptors (Kaumann, 1997). The presence of β 3 ‐adrenoceptors in many tissues, including slow‐contracting skeletal muscle (Challis et al , 1988; Molenaar et al , 1992), has lead to the suggestion that certain pharmacological responses of β‐adrenoceptor agonists may involve mixed receptor populations. Further, it has been shown that some β‐adrenoceptor ligands have different degrees of stereo‐selectivity for β 2 ‐ and β 3 ‐adrenoceptors (Bojanic et al , 1985; Harms, 1976; Harms et al , 1977).…”