Effect of Anaesthetics and Haemorrhage on the Release of Neurohypophysial Antidiuretic Hormone

Abstract

The first demonstration of "physiological" or "pharmacological" activity in extracts from the posterior pituitary gland was made by Oliver and Schafer (1895) when they discovered that these extracts raise the blood pressure. Since then, although the role of neurohypophysial principles in the physiological control of the renal excretion of water and of milk ejection has been well established, very little evidence has been adduced which indicates a physiological role for the pressor action of neurohypophysial antidiuretic hormone.Rydin and Verney (1938) showed that removal of blood from arteries in dogs resulted in an antidiuretic response which they concluded " was humorally determined and that the humoral agent was not adrenaline." Ginsburg and Heller (1953b) found that the antidiuretic activity in blood increased during haemorrhage in anaesthetized rats, and they concluded that there was increased release of antidiuretic hormone from the neurohypophysis.The amounts of antidiuretic hormone found in blood were large enough to suggest that it may have had an effect on blood pressure in these conditions. The effect of haemorrhage on the neurohypophysis has therefore been more fully investigated, with particular reference to the anaesthetics used. METHODSYoung adult rats (170-270 g.) of the albino Wistar strain were anaesthetized with ether, pentobarbitone sodium (65 mg./kg. intraperitoneally), urethane (2.0 g./kg. subcutaneously), chloralose (60-100 mg./kg. intravenously), or ethanol (3-5 ml./kg. intravenously).Ethanol (30% v/v in 0.9% NaCl solution) and chloralose were injected into conscious animals through a polyethylene catheter which had been inserted in a femoral vein under ether anaesthesia 18 hr. previously.The trachea, femoral vein, and the cephalic end of an external jugular vein were cannulated. Blood pressure was recorded from a femoral artery, rather than a carotid artery, in order to avoid disturbance of cerebral circulation." Slow " Haenworrhage.-In most experiments 0.5 ml.blood/100 g. body wt. was withdrawn from the external jugular vein at 4 min. intervals until 5-7 such withdrawals had been made. When blood samples (0.2-0.9 ml.) for biological assay were taken, an equal volume of rat blood was simultaneously returned into the animal through the femoral vein. The first samples for assay were taken two minutes before the first haemorrhage, and subsequent samples were taken in the middle of the interval between haemorrhages." Rapid" Haemorrhage.-In a few experiments the net loss of blood was achieved more quickly and remained more or less constant during the collection of the samples for assay. The barrel of a 10 ml. syringe was attached by polyethylene tubing to a cannula in a femoral artery. The syringe was held lower than the animal and blood was allowed to flow into it. When 5-6 ml. of blood had been withdrawn the syringe was raised so that the level of blood in it was 40-45 cm. above the rat's heart. In this way the blood pressure of the rat was maintained at 32-36 mm. Hg. Samples of blood for ...

The Influence of Anaesthetics on the Increase in the Water Permeability of the Toad Bladder Induced by Vasopressin

“…The anti-diuretic activity of the plasma in the rat, cat and dog is elevated during anaesthesia with ether, urethane and with many barbiturates (Dicker, 1953;Ginsberg & Brown, 1957;Beleslin, Bisset, Haldar & Polak, 1966;Bonjour & Malvin, 1970). Chloralose has been reported not to increase anti-diuretic activity of plasma (Ginsberg & Brown, 1957).…”

“…Chloralose has been reported not to increase anti-diuretic activity of plasma (Ginsberg & Brown, 1957). The marked anti-diuresis which follows administration of morphine has been ascribed to excess release of anti-diuretic hormone (ADH) by the drug (de Bodo, 1944;Duke, Pickford & Watt, 1951).…”

Electrophysiological evidence for the activation of supraoptic neurones during the release of oxytocin

“…Four of the phasically active units were correlated with the oxytocin release for milk ejection. Three of these units displayed a burst of activity superimposed on the terminal portion ofan active phase, some 10 2-14*7 see INTRODUCTION The neurosecretory cells of the paraventricular (PV) and supraoptic (SO) nuclei of the hypothalamus have axons projecting to the neurohypophysis and form the efferent pathway for the neuroendocrine reflexes involved in the release of oxytocin and vasopressin following stimuli such as suckling (Folley & Knaggs, 1966;Bisset, Clark & Haldar, 1970), expansion of the birth canal (Roberts & Share, 1968;Haldar, 1970), dehydration (Jones & Pickering, 1969) and haemorrhage (Ginsburg & Brown., 1956;Bisset, Clark & Errington, 1971). PV and SO units have been identified in many studies by antidromic activation from the neurohypophysis (Yagi, Azuma & Matsuda, 1966;Cross, Novin & Sundsten, 1969) and the characteristics of their antidromic activation have been extensively investigated by extracellular (Dreifuss & Kelly, 1972a, b;Negoro & Holland, 1972;Barker, Crayton & Nicoll, 1971) and intracellular recording (Koizumi & Yamashita, 1972).…”

Plasma oxytocin and oxytocin neurone activity during delivery in rabbits.

“…A statistically significant greater degree of variance of the oxytocin titres was found in plasma samples collected in delivery which implies that the release was pulsatile but not detected for technical reasons. Labour in the rabbit is rapid (an average of seven kittens expelled in 7 min) and with the half-life of oxytocin 1P6-85 min (Ginsburg & Brown, 1956;Ginsburg, 1968) sampling every 10-15 s may not be sufficiently fast to detect discrete pulses of hormone released approximately once a minute. Perhaps the 'spurt-like' release of hormone observed in human labour (Gibbens & Chard, 1976;Otsuki, Yamaji, Fujita, Takagi & Tanizawa, 1983) reflects a longer interval between pulses of hormone released into the circulation by women in delivery.…”