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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possibility of an interaction between oxytocin and aldosterone to influence renal Na+ excretion was investigated in Inactin-anaesthetized male Sprague-Dawley rats. Endogenous plasma concentrations of aldosterone were suppressed by either adrenalectomy or bicarbonate infusion. The effects of 2 h intravenous administration of oxytocin (0.04 pmol/min) and/or aldosterone (42 pmol/min) on renal Na+ handling were studied in 0.077 M NaCl-infused adrenalectomized (Adx) rats and groups of intact animals that were infused with 0.077 M NaHCO3. Aldosterone alone significantly (P < 0.01) reduced Na+ excretion from pretreatment peak value of 5.0 +/- 1.0 to 1.5 +/- 0.4 mumol/min in Adx animals (n = 8) and 9.2 +/- 1.2 to 5.2 +/- 1.2 mumol/min in NaHCO3-infused rats (n = 8) by 2 h after the start of administration. However, combined administration of aldosterone and oxytocin was associated with a significantly (P < 0.01) increased Na+ excretion rate from a peak pretreatment value of 6.8 +/- 0.7 mumol/min to a peak value of 11.5 +/- 1.1 mumol/min by 1 h 40 min after the start of treatment in Adx rats (n = 7). In bicarbonate-infused rats (n = 8) Na+ excretion rose within 20 min of the start of treatment from a pretreatment peak of 9.0 +/- 0.8 mumol/min to a peak value of 13.5 +/- 0.8 mumol/min in response to combined hormone administration. In conclusion, we have shown that concomitant administration of aldosterone and oxytocin increased the rate of excretion of Na+ in two different preparations, which supports the idea of an interaction between the steroid and oxytocin to promote Na+ loss.
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PMID:Interaction of aldosterone and oxytocin to influence renal sodium excretion in rats. 781 65

Neurohypophyseal oxytocin (OT), secreted continuously under conditions of hyperosmolality, is a potent natriuretic hormone in rats. In contrast, OT secretion during lactation is pulsatile and is not accompanied by increased urinary Na+ excretion. The present experiments compared the effects of continuous and pulsatile infusion of OT on natriuresis in rats. In male rats anesthetized with Inactin, continuous infusion of OT (125 ng/kg x h) increased plasma OT to about 70 pg/ml; renal Na+ excretion increased 10-fold, and urine volume and K+ excretion also were elevated. However, when OT was administered i.v. in the same amount but in pulses given once every 5 or 10 min, to simulate the pattern of OT secretion during lactation, rats did not excrete significantly more urine, Na+, or K+ than did vehicle-treated animals. The plasma renin concentration, measured in these experiments because OT receptors are present in the macula densa, increased 2-fold when OT was infused either continuously or in pulses. These results indicate that the effects of OT administration on urinary Na+ excretion in rats varies depending on whether the infusion is pulsatile or continuous, whereas the effects of OT on renin secretion show no such difference.
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PMID:Sodium excretion and renin secretion after continuous versus pulsatile infusion of oxytocin in rats. 1034 72