-Adrenergic receptors on rat ventricular myocytes: characteristics and linkage to cAMP metabolism

Journal Article · Fri Aug 01 00:00:00 EDT 1986 · Am. J. Physiol.; (United States)

OSTI ID:6283512

Buxton, I L.O.; Brunton, L L

When incubated with purified cardiomyocytes from adult rat ventricle, the 1-antagonist (TH)prazosin binds to a single class of sites with high affinity. Competition for (TH)prazosin binding by the 2-selective antagonist yohimbine and the nonselective -antagonist phentolamine demonstrates that these receptors are of the 1-subtype. In addition, incubation of myocyte membranes with (TH)yohimbine results in no measurable specific binding. Agonist competition for (TH)prazosin binding to membranes prepared from purified myocytes demonstrates the presence of two components of binding: 28% of 1-receptors interact with norepinephrine with high affinity (K/sub D/ = 36 nM), whereas the majority of receptors (72%) have a low affinity for agonist (K/sub D/ = 2.2 M). After addition of 10 M GTP, norepinephrine competes for (TH)prazosin binding to a single class of sites with lower affinity (K/sub D/ = 2.2 M). Incubation of intact myocytes for 2 min with 1 M norepinephrine leads to significantly less cyclic AMP (cAMP) accumulation than stimulation with either norepinephrine plus prazosin or isoproterenol. Likewise, incubation of intact myocytes with 10 W M norepinephrine leads to significantly less activation of cAMP-dependent protein kinase than when myocytes are stimulated by both norepinephrine and the 1-adrenergic antagonist, prazosin or the US -adrenergic agonist, isoproterenol. They conclude that the cardiomyocyte 1 receptor is coupled to a guanine nucleotide-binding protein, that 1-receptors are functionally linked to decreased intracellular cAMP content, and that this change in cellular cAMP is expressed as described activation of cAMP-dependent protein kinase.

• Research Organization: Univ. of California, La Jolla
• OSTI ID: 6283512
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 251:2; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMP
ANIMAL CELLS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CARDIOVASCULAR SYSTEM
DRUGS
ENZYMES
HEART
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
METABOLISM
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PHYSIOLOGY
RADIORECEPTOR ASSAY
RATS
RECEPTORS
RODENTS
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS
VERTEBRATES