Demonstration of. beta. /sub 1/-adrenoceptor mediating relaxation of porcine coronary artery by radioligand binding and pharmacological methods

Journal Article · Fri Jan 01 04:00:00 EST 1988 · Life Sci.; (United States)

DOI:https://doi.org/10.1016/0024-3205(88)90573-5· OSTI ID:6208071

Yamada, S; Kashiwabara, T; Yamazawa, T; Harada, Y; Nakayama, K

..beta..-adrenoceptors in the porcine coronary artery were characterized by a radioligand binding assay using (-)-(/sup 3/H)dihydroalprenolol (DHA) and also by measuring the relaxant response of isolated coronary artery to norepinephrine. Specific (-)-(/sup 3/H)DHA binding in the porcine coronary artery was saturable, reversible and of high affinity with a maximal number of binding sites of 63 fmol/mg protein, and it showed a pharmacological specificity as well as stereoselectivity which characterized ..beta..-adrenoceptors. The Hofstee analysis of inhibition of (-)-(/sup 3/H)DHA binding by atenolol, practolol and ICI 118551 has shown that the averaged concentration of ..beta../sub 1/ and ..beta../sub 2/-adrenoceptors in this tissue was 68% and 32% respectively. The relaxant response of isolated coronary artery to norepinephrine was competitively antagonized by (-)propranolol, (+)propranolol, atenolol, practolol and ICI 118551. The pA/sub 2/ values of these adrenoceptor antagonists were significantly correlated with the Ki values for ..beta../sub 1/ but not ..beta../sub 2/-adrenoceptors determined by the (-)-(/sup 3/H)DHA binding assay. Thus, the present study demonstrates that the relaxant response of porcine coronary artery to norepinephrine is predominantly mediated through the stimulation of ..beta../sub 1/-adrenoceptors on vascular smooth muscles.

• Research Organization: Univ. of Shizuoka (Japan)
• OSTI ID: 6208071
• Journal Information: Life Sci.; (United States), Journal Name: Life Sci.; (United States) Vol. 43:24; ISSN LIFSA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ANIMALS
ARTERIES
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
BLOOD VESSELS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CHEMICAL COMPOSITION
CORONARIES
DOMESTIC ANIMALS
DRUGS
FUNCTIONS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIGANDS
MAMMALS
MEMBRANE PROTEINS
NEUROREGULATORS
NORADRENALINE
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIORECEPTOR ASSAY
REACTION KINETICS
RECEPTORS
SWINE
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES