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To investigate the pulsatile nature of basal and stimulated renin and aldosterone secretion, we sampled blood for plasma renin activity (PRA) and plasma aldosterone concentration at 10-min intervals for 24 h in nine normal supine human male subjects after equilibration in high- and low-sodium balance states. We evaluated serial hormonal measures by a quantitative waveform-independent deconvolution technique designed to compute the number, amplitude, and mass of underlying secretory bursts and simultaneously to estimate the presence and extent of basal secretion. For both PRA and aldosterone: 1) burstlike release accounted for greater than or equal to 60% of total secretion and tonic release for less than 40%; 2) there was an 80- to 85-min interpulse interval unchanged by sodium intake; 3) sodium restriction engendered an increase in plasma hormone concentrations by increasing the amount and maximal rate of hormone secreted per burst; 4) low dietary sodium also induced increases in basal hormone secretory rates, suggesting that there may be two regulatory processes driving renin and aldosterone secretion; and 5) PRA was significantly coupled to plasma aldosterone concentration by a 0-, 10-, or 20-min aldosterone lag time in both high- and low-sodium balance. We conclude that both renin and aldosterone are released via a predominantly burstlike mode of secretion; PRA and plasma aldosterone concentrations are positively coupled by a short time lag (0-20 min); and sodium restriction achieves an increase in mean PRA and plasma aldosterone concentration by selective amplitude enhancement of individual hormone secretory bursts and by increased tonic (interburst) basal secretory rates.
Vieweg et al. (Fri,) studied this question.