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Effect of atrial natriuretic factor on calcium fluxes in adrenal glomerulosa cells
M Takagi1, M Takagi, R Franco-Saenz
1Department of Internal Medicine, Medical College of Ohio, Toledo 43699.
Abstract:
We studied the effect of atrial natriuretic factor (ANF) on calcium influx and efflux in rat adrenal glomerulosa cells stimulated by angiotensin II (Ang II) or potassium ion, and observed how ANF inhibits the initial and sustained phases of the aldosterone response to Ang II or K+ using a superfusion system of dispersed adrenal glomerulosa cells. K+ (8 mM) significantly increased Ca2+ influx rate compared with basal rate (0.91 +/- 0.10 vs 0.42 +/- 0.04 nmol/min/10(6) cells; p less than 0.01). ANF (10(-8) M) did not inhibit the K+-induced increase in Ca2+ influx rate (0.99 +/- 0.18 nmol/min/10(6) cells). Ang II (10(-9) and 10(-8) M) stimulated Ca2+ influx rate (10(-9) M Ang II, 0.62 +/- 0.02; 10(-8) M Ang II, 0.71 +/- 0.09 vs basal, 0.44 +/- 0.03 nmol/min/10(6) cells; p less than 0.05), while ANF (10(-8) M) did not change the Ca2+ influx rate increased by Ang II (ANF + 10(-9) M Ang II, 0.62 +/- 0.06; ANF + 10(-8) M Ang II, 0.69 +/- 0.14 nmol/min/10(6) cells). In the Ca2+ efflux study ANF (10(-8) M) was perfused through the cells 10 minutes before the start of perfusion with Ang II (10(-9) M) or K+ (12 mM).(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Atrial natriuretic factor (ANF) does not affect calcium influx stimulated by angiotensin II (Ang II) or potassium ions in rat adrenal cells. This study investigates ANF's role in aldosterone regulation.
Area of Science:
- Endocrinology
- Cell Physiology
Background:
- Aldosterone production is regulated by angiotensin II (Ang II) and potassium ions.
- Calcium influx is a critical component of the aldosterone response.
- Atrial natriuretic factor (ANF) is a hormone with known effects on cardiovascular and endocrine systems.
Purpose of the Study:
- To investigate the effect of atrial natriuretic factor (ANF) on calcium (Ca2+) influx and efflux in rat adrenal glomerulosa cells.
- To determine if ANF modulates the aldosterone response to Ang II or potassium (K+).
Main Methods:
- Utilized a superfusion system with dispersed rat adrenal glomerulosa cells.
- Measured Ca2+ influx and efflux rates under basal conditions and in response to Ang II or K+ stimulation.
- Assessed the impact of ANF (10(-8) M) on these responses.
Main Results:
- Potassium (8 mM) significantly increased Ca2+ influx rate (p < 0.01).
- ANF did not inhibit the K+-induced increase in Ca2+ influx.
- Ang II (10(-9) and 10(-8) M) stimulated Ca2+ influx (p < 0.05), and ANF did not alter this Ang II-mediated increase.
- The abstract was truncated before Ca2+ efflux results could be detailed.
Conclusions:
- ANF does not appear to inhibit the initial calcium influx stimulated by Ang II or K+ in rat adrenal glomerulosa cells.
- The mechanism by which ANF inhibits aldosterone response to Ang II or K+ may not involve direct modulation of Ca2+ influx.