Effects of PTH and Ca/sup 2 +/ on renal adenyl cyclase

Journal Article · Sun Jan 01 04:00:00 EST 1978 · J. Supramol. Struct.; (United States)

DOI:https://doi.org/10.1002/jss.400090309· OSTI ID:5734541

Nielsen, S T; Neuman, W F

The effects of calcium ion on the adenylate cyclase system was studied in isolated, renal basal-lateral plasma membranes of the rat. Bovine parathyroid hormone (bPTH) and a guanyl triphosphate analogue, Gpp(NH)p were used to stimulate cyclase activity. Under conditions of maximal stimulation, calcium ions inhibited cyclic adenosine monophosphate (cAMP) formation, the formation rate falling exponentially with the calcium concentration. Fifty percent inhibition of either bPTH- or Gpp(NH)p-stimulated activity was given by approximately 50 ..mu..M Ca/sup 2 +/. Also the Hill coefficient for the inhibition was close to unity in both cases. The concentration of bPTH giving half-maximal stimulation of cAMP formation (1.8 x 10/sup -8/M) was unchanged by the presence of calcium. These data suggest that calcium acts at some point other than the initial hormone-receptor interaction, presumably decreasing the catalytic efficiency of the enzymic moiety of the membrane complex.

• Research Organization: Univ. of Rochester Medical Center, NY
• OSTI ID: 5734541
• Journal Information: J. Supramol. Struct.; (United States), Journal Name: J. Supramol. Struct.; (United States) Vol. 9; ISSN JSPMA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
AMP
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BODY
CALCIUM
CELL CONSTITUENTS
CELL MEMBRANES
DOSE-RESPONSE RELATIONSHIPS
ELEMENTS
ENZYMES
HORMONES
INHIBITION
KIDNEYS
KINETICS
MAMMALS
MEMBRANES
METALS
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
PARATHORMONE
PEPTIDE HORMONES
RATS
REACTION KINETICS
RODENTS
VERTEBRATES