Supersensitivity of beta-adrenoceptor coupled adenylate cyclase in pulmonary tissue of the spontaneously hypertensive rat

Journal Article · Sat Dec 31 23:00:00 EST 1988 · Life Sciences; (USA)

DOI:https://doi.org/10.1016/0024-3205(89)90077-5· OSTI ID:7027005

Kamibayashi, C; Ramanathan, S ^[1]

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1. Univ of Hawaii, Honolulu (USA)

Basal adenylate cyclase activity was similar in plasma membranes prepared from the lungs of 12 week old spontaneously hypertensive rats (SHR) and normotensive Wister Kyoto rats (WKY). However, sensitivity to Gpp (NH)p, isoproterenol plus GTP or Gpp (NH)p was significantly greater in the SHR. Beta-receptor density measured by ({sup 3}H)DHA binding was unaltered. The dissociation constant, K{sub d}, revealed a significantly greater binding affinity of the radioligand in the SHR compared with the WKY. Activity of G{sub s} was assessed by complementing S49 cyc{sup {minus}} acceptor membranes with lung cholate extract. Basal activity of the reconstituted system was decreased 43% in the SHR. However, sensitivity to NaF, Gpp(NH)p, and isoproterenol plus Gpp(NH)p was significantly elevated. These data suggest that desensitization of the adenylate cyclase complex is not a generalized response to chronic hypertension. A tissue specific increase in sympathetic drive appears to be responsible for the lowered concentration of cardiac beta-adrenoceptors in the SHR. In contrast, both indirect and direct evidence indicate an enhanced functional sensitivity of pulmonary G{sub s} in the hypertensive rats.

• OSTI ID: 7027005
• Journal Information: Life Sciences; (USA), Journal Name: Life Sciences; (USA) Vol. 45:22; ISSN 0024-3205; ISSN LIFSA
• Country of Publication: United States
• Language: English

Related Subjects

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550901 -- Pathology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL VARIABILITY
BODY
CARDIOVASCULAR DISEASES
CELL CONSTITUENTS
CELL MEMBRANES
CYCLASES
DISEASES
DRUGS
ENZYME ACTIVITY
ENZYMES
GENETIC VARIABILITY
HYDROGEN COMPOUNDS
HYPERTENSION
ISOTOPE APPLICATIONS
KINETICS
LUNGS
LYASES
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
ORGANIC COMPOUNDS
ORGANS
PATHOGENESIS
PROTEINS
RATS
REACTION KINETICS
RECEPTORS
RESPIRATORY SYSTEM
RODENTS
SYMPATHOMIMETICS
SYMPTOMS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VASCULAR DISEASES
VERTEBRATES