Na(+)-H+ exchanger kinetics in adrenal glomerulosa cells and its activation by angiotensin II

Journal Article · Sun Jul 01 04:00:00 EDT 1990 · Endocrinology; (USA)

DOI:https://doi.org/10.1210/endo-127-1-236· OSTI ID:6611261

Conlin, P R; Kim, S Y; Williams, G H; Canessa, M L ^[1]

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1. Brigham and Women's Hospital, Boston, MA (USA)

We have studied the kinetic properties of basal and angiotensin II (ANG II) stimulated Na(+)-H+ exchange in adrenal glomerulosa cells by measuring changes in cytosolic pH (pHi) and initial rates of 22Na uptake in the presence or absence of dimethylamiloride (DMA). The cells were studied under basal conditions, at constant pHi with varied external sodium (Na+o), and at varied pHi with constant Na+o (50 mM). In 2,7-biscarboxyethyl-5(6)-carboxyfluorescein loaded cells under basal conditions, pHi rose from 7.09 +/- 0.02 to 7.19 +/- 0.02. Similarly, DMA-sensitive Na influx was enhanced from 9.2 +/- 1.3 to 14.8 +/- 2.1 nmol Na+/mg protein x min (P less than 0.01) by ANG II. In cells acid-loaded by preincubation in Na(+)-free media (pHi 6.8), addition of varying Na+o resulted in a rapid H+ efflux that was markedly inhibited by DMA. DMA-sensitive Na+ influx into these acidified cells with varied Na+o exhibited a Michaelis-Menten constant (Km) of 23 mM and a maximum velocity (Vmax) of 43 nmol Na+/mg protein x min. By varying pHi (from pHi 7.1 to 6.2), DMA-sensitive Na+ influx likewise showed activation with cellular acidification with a pK at pHi 7.09. At pHi 6.8, ANG II decreased the Km for Na+o from 23 to 17 mM and increased the Vmax from 43 to 53 nmol Na+/mg protein x min. The pHi dependence of DMA-sensitive Na+ influx was not affected by ANG II (pK at pHi 7.03). DMA also inhibited AII-stimulated aldosterone secretion and Na+ influx similarly. These results indicate that Na(+)-H+ exchange in adrenal glomerulosa cells is functioning under basal conditions, and is modulated by ANG II with enhanced Na+o affinity and Vmax but without a shift in pHi dependence (similar to ANG II effects on vascular smooth muscle cells). These effects suggest an important role for Na(+)-H+ exchange during ANG II stimulation of aldosterone production by glomerulosa cells.

• OSTI ID: 6611261
• Journal Information: Endocrinology; (USA), Journal Name: Endocrinology; (USA) Vol. 127:1; ISSN ENDOA; ISSN 0013-7227
• Country of Publication: United States
• Language: English

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550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL GLANDS
ADRENAL HORMONES
ALDEHYDES
ALDOSTERONE
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANGIOTENSIN
ANIMALS
AROMATICS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
BIOSYNTHESIS
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR AGENTS
CATTLE
CORTICOSTEROIDS
DIURETICS
DOMESTIC ANIMALS
DRUGS
DYES
ENDOCRINE GLANDS
FLUORESCEIN
FUNCTIONS
GLANDS
GLOBULINS
HYDROXY ACIDS
HYDROXY COMPOUNDS
ION EXCHANGE
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KETONES
KINETICS
LIGHT NUCLEI
MAMMALS
MEMBRANE TRANSPORT
MINERALOCORTICOIDS
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PH VALUE
PHENOLS
POLYPHENOLS
PREGNANES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RUMINANTS
SODIUM 22
SODIUM COMPOUNDS
SODIUM ISOTOPES
STEROIDS
SYNTHESIS
TRACER TECHNIQUES
VASOCONSTRICTORS
VERTEBRATES
YEARS LIVING RADIOISOTOPES