The Assay of Milk‐ejecting Activity in the Lactating Rat

Bisset, G. W.; Clark, Barbara J.; Haldar, Jaya; Harris, Mary; Lewis, George; Silva, M. Rocha e

doi:10.1111/j.1476-5381.1967.tb00418.x

Cited by 81 publications

(54 citation statements)

References 25 publications

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“…The released neurohypophysial hormones were estimated by the rat milk ejection method (Bisset et al, 1967) using Pitocin (Parke, Davis & Co., Detroit, Mich.) as a reference standard. It should be pointed out that this assay measures both oxytocin and vasopressin at a ratio of about 7:1.…”

Section: Hormone Assaymentioning

confidence: 99%

Effects of veratridine on Ca fluxes and the release of oxytocin and vasopressin from the isolated rat neurohypophysis.

Nordmann¹,

Dyball²

1978

The Journal of General Physiology

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A B S T R A C T Uptake of radioactive calcium, 4~Ca efflux, and hormone release from the isolated rat neurohypophysis were monitored in vitro after the addition of veratridine to the incubation medium. Veratridine dramatically increased hormone release, but the release rate was not sustained and had declined by about 90% after 2 h. Removal of external Na § prevented hormone release as did addition to the incubation medium of tetrodotoxin or the calcium antagonists D600 and Mn z+ ions. Veratridine increased 45Ca uptake into the isolated neurohypophysis and the increase could be prevented by addition of tetrodotoxin or D600 to the medium. Efflux of 4SCa was not changed by addition of veratridine. The results underline the importance of both Na + and Ca +2 channels in the regulation of secretion of neurosecretory products.

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Section: Hormone Assaymentioning

confidence: 99%

Effects of veratridine on Ca fluxes and the release of oxytocin and vasopressin from the isolated rat neurohypophysis.

Nordmann¹,

Dyball²

1978

The Journal of General Physiology

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“…In addition the methods for extraction and assay of neurohypophysial hormones have been improved (Bisset, Clark, Haldar, Harris, Lewis & Rocha e Silva, 1967;Bisset, Hilton & Poisner, 1967). It seemed important therefore to apply these techniques to a more critical investigation of the nature of the relationship between the electrical and secretary properties of neurosecretory neurones.…”

Section: Introductionmentioning

confidence: 99%

Oxytocin and ADH secretion in relation to electrical activity in antidromically identified supraoptic and paraventricular units

Dyball¹

1971

The Journal of Physiology

113

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SUMMARY1. Electrical recordings were made from antidromically identified supraoptic and paraventricular units during intracarotid injections of hypertonic and isotonic sodium chloride solutions in rats.2. The blood concentrations of vasopressin and oxytocin were estimated by bio-assay before and at different intervals after similar injections.3. Although a significant change in the action potential activity of the supraoptic nucleus was associated with hormone release, the results were not entirely consistent with a simple relationship between action potential activity and hormone secretion. Firstly, although some units were excited by the stimulus a substantial number were inhibited. Secondly, the blood concentration of the hormones, particularly ADH, remained elevated for longer than might have been expected if additional hormone had ceased to be secreted as soon as firing rates had returned to control values.4. There were substantial differences between the initial blood concentrations of vasopressin and oxytocin but the firing rates of units in the supraoptic and paraventricular nuclei appeared to be the same.5. Although significantly less paraventricular than supraoptic units were affected by hypertonic injections the blood concentration of oxytocin was increased bv a factor of 8 whereas that of vasopressin was increased by a factor of 2-7.

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“…The teat of the anaesthetized lactating animal is cannulated, oxytocin is injected into the blood stream and changes in the pressure are recorded. Suitable animals are the rabbit (Fitzpatrick, 1961), guinea-pig (Tindal & Yokoyama, 1962) and rat (Bisset, Clark, Haldar, Harris, Lewis & Rocha e Silva, 1967). It is possible to obtain greater sensitivity by giving injections directly into the arterial supply, so that the oxytocin reaches its site of action in higher concentrations (Fitzpatrick, 1961; Bisset et al, 1967).…”

Section: Discussionmentioning

confidence: 99%

“…Suitable animals are the rabbit (Fitzpatrick, 1961), guinea-pig (Tindal & Yokoyama, 1962) and rat (Bisset, Clark, Haldar, Harris, Lewis & Rocha e Silva, 1967). It is possible to obtain greater sensitivity by giving injections directly into the arterial supply, so that the oxytocin reaches its site of action in higher concentrations (Fitzpatrick, 1961; Bisset et al, 1967). Other workers have used the mammary gland in vitro; a strip of tissue is suspended in an organ bath, and the increases in tension caused by oxytocin are recorded (Mendez-Bauer, Cabot & CaldeyroBarcia, 1960;Ryden & Sj6holm, 1962;Roca et al, 1972 between the application of oxytocin and the expulsion of droplets of milk is related to the concentration of hormone applied (Van Dongen & Hays, 1966).…”

Section: Discussionmentioning

confidence: 99%

Bioassay of Oxytocin on the Superfused Mammary Gland of the Mouse, Using an Automatic Apparatus

Robinson¹,

Walker²

1974

British J Pharmacology

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A sensitive method of assaying oxytocin using the superfused mouse mammary gland is described. The method is shown to be reliable, accurate and precise. Assays are performed automatically and the preparation is stable for at least 18 hours. The preparation is relatively insensitive to bradykinin, histamine, 5‐hydroxytryptamine, angiotensin, prostaglandin F2α, adrenaline and noradrenaline. The contractions produced by acetylcholine can be abolished by atropine without the sensitivity to oxytocin being affected. Vasopressin has a variable activity on the preparation; its potency can be as high as one‐fifth that of oxytocin. It is concluded that this method compares favourably with other published methods.

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The Assay of Milk‐ejecting Activity in the Lactating Rat

Cited by 81 publications

References 25 publications

Effects of veratridine on Ca fluxes and the release of oxytocin and vasopressin from the isolated rat neurohypophysis.

Effects of veratridine on Ca fluxes and the release of oxytocin and vasopressin from the isolated rat neurohypophysis.

Oxytocin and ADH secretion in relation to electrical activity in antidromically identified supraoptic and paraventricular units

Bioassay of Oxytocin on the Superfused Mammary Gland of the Mouse, Using an Automatic Apparatus

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