Partial Agonistic Effects of Carteolol on Atypical β-Adrenoceptors in the Guinea Pig Gastric Fundus

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Abstract

The properties of the β<SUB>1</SUB>-/β<SUB>2</SUB>-adrenoceptor partial agonist carteolol were investigated in atypical β-adrenoceptors on the guinea pig gastric fundus. Carteolol induced concentration-dependent relaxation in this tissue (pD<SUB>2</SUB>=5.55, intrinsic activity=0.94). However, a combination of the selective β<SUB>1</SUB>-adrenoceptor antagonist atenolol (100 μM) and the selective β<SUB>2</SUB>-adrenoceptor antagonist butoxamine (100 μM) produced only small rightward shifts in the concentration-response curves of carteolol in the gastric fundus (pD<SUB>2</SUB>=4.91, intrinsic activity=0.94). In the presence of both atenolol (100 μM) and butoxamine (100 μM), the non-selective β<SUB>1</SUB>-, β<SUB>2</SUB>- and β<SUB>3</SUB>-adrenoceptor antagonist (±)-bupranolol (10-100 μM) caused a concentration-dependent right-ward shift of the concentration-response curves for carteolol in the guinea pig gastric fundus. Schild plot analyses of the effects of (±)-bupranolol against carteolol gave the pA<SUB>2</SUB> value of 5.29 and the Schild slope was not significantly different from unity. Furthermore, carteolol (10 μM) weakly but significantly antagonized the relaxant responses to catecholamines ((−)-isoprenaline, (−)-noradrenaline and (−)-adrenaline), a selective β<SUB>3</SUB>-adrenoceptor agonist BRL37344 ((R<SUP>*</SUP>, R<SUP>*</SUP>)-(±)-4-[2-[(2-(3-chlorophenyl)-2-hydroxyethyl)amino]propyl]phenoxyacetic acid sodium salt) and a non-conventional partial β<SUB>3</SUB>-adrenoceptor agonist (±)-CGP12177A ([4-[3-[(1, 1-dimethylethyl)amino]-2-hydroxypropoxy]-1, 3-dihydro-2H-benzimidazol-2-one] hydrochloride) in the guinea pig gastric fundus. These results suggest that the partial agonistic effects of carteolol are mediated by atypical β-adrenoceptors in the guinea pig gastric fundus.

Journal

  • The Japanese Journal of Pharmacology

    The Japanese Journal of Pharmacology 84(3), 287-292, 2000-11-01

    The Japanese Pharmacological Society

References:  23

Cited by:  2

Codes

  • NII Article ID (NAID)
    10008186158
  • NII NACSIS-CAT ID (NCID)
    AA00691188
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    00215198
  • NDL Article ID
    5586853
  • NDL Source Classification
    ZS51(科学技術--薬学)
  • NDL Call No.
    Z53-D199
  • Data Source
    CJP  CJPref  NDL  J-STAGE 
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