Changes in expression of a functional G sub i protein in cultured rat heart cells
- Univ. of Maryland School of Medicine, Baltimore (USA)
The muscarinic cholinergic agonist, carbachol, and pertussis toxin were used to examine the functional status of the guanine nucleotide-binding protein that inhibits adenylate cyclase (G{sub i}) in cultured neonatal rat heart myocytes. The isoproterenol stimulation of adenylate cyclase activity in myocyte membranes and adenosine 3{prime},5{prime}-cyclic monophosphate (cAMP) accumulation in intact cells (4 days in culture) were insensitive to carbachol. However, in cells cultured for 11 days, carbachol inhibited isoproterenol-stimulated cAMP accumulation by 30%. Angiotensin II (ANG II) was also found to inhibit isoproterenol-stimulated cAMP accumulation in day 11 cells in a dose-dependent manner. Pertussis toxin treatment reversed the inhibitory effects of both ANG II and carbachol, suggesting a role for G{sub i} in the process. Carbachol binding to membranes from day 4 cells was relatively insensitive to guanine nucleotides when compared with binding to membranes from day 11 or adult cells. Furthermore, pertussis toxin-mediated {sup 32}P incorporation into a 39- to 41-kDa substrate in day 11 membranes was increased 3.2-fold over that measured in day 4 membranes. These findings support the view that, although G{sub i} is expressed, it is nonfunctional in 4-day-old cultured neonatal rat heart myocytes and acquisition of functional G{sub i} is dependent on culture conditions. Furthermore, the ANG II receptor can couple to G{sub i} in heart.
- OSTI ID:
- 7192026
- Journal Information:
- American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 255:1; ISSN 0002-9513; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METAL COMPOUNDS
AMINES
ANGIOTENSIN
ANIMAL CELLS
ANIMALS
ANTIGENS
AROMATICS
AZAARENES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BODY
CARDIOVASCULAR AGENTS
CARDIOVASCULAR SYSTEM
CATIONS
CELL CULTURES
CHARGED PARTICLES
CHEMISTRY
CYCLASES
DAYS LIVING RADIOISOTOPES
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ENZYMES
GLOBULINS
GUANINE
HEART
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
IONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LYASES
MAGNESIUM COMPOUNDS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PROTEINS
PURINES
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
TOXIC MATERIALS
TOXINS
TRITIUM COMPOUNDS
UPTAKE
VASOCONSTRICTORS
VERTEBRATES