Determination of molecular size of alpha-1 and alpha-2 adrenoceptors in rat mesenteric artery by radiation inactivation

Journal Article · Sat Mar 01 04:00:00 EST 1986 · J. Pharmacol. Exp. Ther.; (United States)

OSTI ID:5675443

Agrawal, D K; Grover, A K; Daniel, E E; Jung, C Y

Radiation inactivation of alpha-1 and alpha-2 adrenoceptors in the purified plasma membranes of rat mesenteric artery has been performed with high energy electrons at -45 to -55 degrees C. Alpha-1 and alpha-2 adrenoceptor inactivation was monitored with (3H) prazosin and (3H)yohimbine binding, respectively. Internal endogenous and external standards of known molecular weight were used in these studies to determine the molecular size. The average value of D37 for the (3H)prazosin binding site was 6.75 +/- 0.62 Mrad (n = 4) with an estimated molecular size of 122,921 +/- 11,329 Daltons. However, the average value of D37 for the (3H) yohimbine binding site was higher (D37 = 10.05 +/- 0.91 Mrad) and accordingly the molecular size of this binding site was less than the (3H)prazosin binding sites (molecular weight = 82,540 +/- 7478 Daltons; n = 4). Irradiation did not change the dissociation constant of either radioligand, suggesting that the loss of the radioligand binding sites after radiation is due to receptor protein inactivation. These results confirm our earlier finding that (3H)prazosin and (3H)yohimbine bind to two distinct sites in the plasma membranes of rat mesenteric artery. Whether both of these sites are the subunits of a common macromolecule of alpha adrenoceptor on vascular smooth muscle in rat mesenteric artery cannot be concluded from these results. This report is the first one in the literature on the molecular size of alpha-1 and alpha-2 binding sites in vascular smooth muscle.

• Research Organization: McMaster Univ., Hamilton, Ontario
• OSTI ID: 5675443
• Journal Information: J. Pharmacol. Exp. Ther.; (United States), Journal Name: J. Pharmacol. Exp. Ther.; (United States) Vol. 3; ISSN JPETA
• Country of Publication: United States
• Language: English

Related Subjects

560152* -- Radiation Effects on Animals-- Animals
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADRENAL HORMONES
ADRENALINE
ANIMALS
ARTERIES
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BLOOD VESSELS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CELL MEMBRANES
DRUGS
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HORMONES
IN VITRO
INACTIVATION
LABELLED COMPOUNDS
LEPTONS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MOLECULAR WEIGHT
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIATION EFFECTS
RATS
RECEPTORS
RODENTS
STEROID HORMONES
SYMPATHOMIMETICS
TRITIUM COMPOUNDS
VERTEBRATES