alpha. -Adrenergic vasoconstriction and receptor subtypes in large coronary arteries of calves

Journal Article · Thu Dec 01 04:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6252522

Young, M A; Vatner, D E; Knight, D R; Graham, R M; Homcy, C J; Vatner, S F ^[1]

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1. Massachusetts General Hospital, Boston (USA) New England Regional Primate Research Center, Southborough, MA (USA)

The authors investigated {alpha}-adrenoceptor subtype distribution in large coronary arteries from both functional and biochemical perspectives. The effects of intracoronary administration of the selective {alpha}{sub 1}-adrenoceptor agonist phenylephrine, of the selective {alpha}{sub 2}-adrenoceptor agonist B-HT 920 and of the mixed {alpha}{sub 1+2}-adrenoceptor agonist norepinephrine were examined on measurements of left circumflex coronary artery diameter in conscious calves. After {beta}-adrenergic blockade, equivalent reductions in large coronary artery diameter were observed with phenylephrine, B-HT, and norepinephrine. Phenylephrine-induced constrictions were abolished by prazosin, an {alpha}{sub 1}-selective antagonist, but unaffected by rauwolscine, an {alpha}{sub 2}-selective antagonist. Conversely, the B-HT-induced constriction was abolished by rauwolscine but unaffected by prazosin. Coronary constriction with norepinephrine was attenuated with either prazosin or rauwolscine and abolished by the two antagonists combined. Ligand-binding studies in which ({sup 3}H)prazosin and ({sup 3}H)rauwolscine and sarcolemmal membranes were used revealed an {alpha}{sub 1}-adrenoceptor density of 15 {plus minus} 3.1 fmol/mg protein with a dissociation constant (K{sub D}) of 0.7 {plus minus} 0.2 nM and an {alpha}{sub 2}-adrenoceptor density of 68 {plus minus} 5.1 fmol/mg protein, with a K{sub D} of 7.4 {plus minus} 1.2 nM. Thus large coronary arteries of the calf contain both {alpha}{sub 1}- and {alpha}{sub 2}-adrenoceptor subtypes, each of which elicits constriction of the large coronary artery in the conscious animal.

• OSTI ID: 6252522
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 255:6; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
ARTERIES
BLOOD VESSELS
BODY
CALVES
CARDIOVASCULAR SYSTEM
CATTLE
CHEMICAL REACTIONS
CORONARIES
CROSS-LINKING
DISTRIBUTION
DOMESTIC ANIMALS
HYDROGEN COMPOUNDS
LIGANDS
MAMMALS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
ORGANS
PHYSIOLOGY
POLYMERIZATION
PROTEINS
RECEPTORS
RUMINANTS
TISSUE DISTRIBUTION
TRITIUM COMPOUNDS
VASOCONSTRICTION
VERTEBRATES