Search results for "Vasopressin secretion"
showing 3 items of 3 documents
Modulation by fenoldopam (SKF 82526) and bromocriptine of the electrically evoked release of vasopressin from the rat neurohypophysis. Effects of dop…
1986
1. Single neurointermediate lobes were fixed by their stalks to a platinum wire electrode and incubated in Krebs-bicarbonate solution. Vasopressin release into the medium was determined by a radioimmunoassay. Vasopressin secretion was increased by electrical stimulation (15 Hz, 10 s trains with 10 s intervals for 10 min). 2. Fenoldopam (SKF 82526) had a dual effect on vasopressin release, 30 nM decreasing (by 30%) and 3 μM increasing (by 32%) the evoked vasopressin secretion. The facilitatory effect of fenoldopam was antagonized in a concentration-dependent manner by flupenthixol but not by sulpiride. Sulpiride (1 μM) prevented the inhibitory effect of fenoldopam (30 μM). 3. After pretreatm…
Effects of tetraethylammonium ions on frequency-dependent vasopressin release from the rat neurohypophysis.
1988
1. Isolated rat neurohypophyses were fixed by their stalks to a platinum wire electrode and superfused with oxygenated Krebs-HEPES solution. Vasopressin release into the medium was determined by radioimmunoassay. Vasopressin secretion was increased by electrical stimulation at different frequencies (3-30 Hz) and different train lengths (75-900 pulses). The effects of tetraethylammonium (TEA) ions and of enhanced calcium were tested. 2. Electrical stimulation at 7.5 or 15 Hz evoked a markedly larger release of vasopressin than stimulation at 3 Hz. During continuous stimulation at 7.5 and 15 Hz the evoked vasopressin release per pulse declined rapidly, but with similar time constants for both…
Isoprenaline and forskolin increase evoked vasopressin release from rat pituitary
1982
Isolated neurointermediate lobes of rat pituitaries were incubated in Krebs solution. The vasopressin release evoked by electrical stimulation (0.2 ms, 80 V, 15 Hz, 10 s trains at 10 s intervals for a total of 10 min) was completely inhibited by tetrodotoxin. Isoprenaline increased the evoked vasopressin release to a maximum of 60% (EC50 10 nM) and this effect was antagonized surmountably by propranolol. Forskolin increased the vasopressin release by 98%. These results suggest the presence within the neurohypophysis of a beta-adrenoceptor-linked adenylate cyclase facilitating vasopressin secretion.