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Biomedical subjects

D Pollock

Publications and source records attributed to D Pollock.

At least 73 records · Page 4Linked to original sources
PubMed1975

Reduction in the cholinesterase activity of the rat anococcygeus muscle produced by corticosterone.

1 Administration of corticosterone caused a 47% reduction in the cholinesterase (ChE) activity of homogenates of the rat anococcygeus muscle. 2 ChE activity was also reduced by morphine withdrawal and this effect was abolished by the corticosteroid synthesis inhibitor, metyrapone. 3 A single dose of reserpine reduced ChE activity in normal but not in adrenalectomized rats. 4 ChE activity was increased by adrenalectomy or by metyrapone treatment. 5 The mechanism of the corticosteroid-induced reduction in ChE activity is discussed. 6 The reduction in ChE activity produced by corticosterone, morphine withdrawal, or a single dose of reserpine might explain the leftward shift of the dose-% response curve to acetylcholine produced by these procedures in the isolated anococcygeus muscle of the rat.

Adrenal Glands↗
PubMed1975

The involvement of corticosteroids in the supersensitivity produced in the rat anococcygeus muscle by morphine withdrawal, thyroidectomy or a single dose of reserpine.

The effects of chronically administered corticosterone on the responses of the rat isolated anococcygeus muscle to agonists (acetylcholine, norepinephrine) were compared with those of morphine withdrawal in intact or metyrapone-pretreated rats and with those of a single dose of reserpine in intact or adrenalectomized rats. The possibility that the similar supersensitivity, which occurs in thyroidectomized rats, might be associated with elevated corticosterone levels was investigated by measuring fluorimetrically the plasma levels of corticosterone in thyroidectomized rats. Corticosterone, morphine withdrawal or a single dose of reserpine produced similar supersensitivities, characterized by increased maximum responses to both agonists (acetylcholine, norepinephrine) and an increased pD2 value for acetylcholine. This effect of morphine withdrawal together with the weight loss characteristic of this condition was absent in metyrapone-pretreated rats. A single dose of reserpine had no effect in adrenalectomized rats. Plasma corticosterone levels were elevated in thyroidectomized rats. These results suggest that the common factor underlying the identical supersensitivities produced by corticosterone, morphine withdrawal, a single dose of reserpine or thyroidectomy is the ability of each treatment to raise plasma corticosterone levels.

Acetylcholine↗
PubMed1975

The effects of electrical stimulation of the autonomic nerves and of drugs on the size of salivary glands and their rate of cell division.

The effects of electrical stimulation of the sympathetic and of the parasympathetic nerves on the size of rat salivary glands have been investigated and compared with those caused by isoproterenol. Sympathetic nerve stimulation increased the size and the mitotic index in the parotid acini; in the submaxillary acini, only the size was increased. These responses varied with the gland studied and the duration of stimulation; the parotid showed the larger increase in the mitotic index and thymidine uptake, the submaxillary the greater degree of cell enlargement. Prolonged electrical stimulation beyond that required to produce the maximum increase in size reduced the enlargement. Sympathetic nerve stimulation caused no enlargement in the extraorbital lacrimal or major sublingual glands. The responses to sympathetic nerve stimulation were inhibited by propranolol (17 nmol/pg), normetanephrine (2 X 45 nmol/g) and mecamylamine (50 nmol/g) but not by phentolamine (13.0 nmol/g) or atropine (7.5 nmol/g). Electric stimulation of the parasympathetic nerves produced no increase in the size or in the mitotic index.

Animals↗
PubMed1973

The effects of drugs on the sensitivity of the rat anococcygeus muscle to agonists.

1. The effects of cocaine, 6-hydroxydopamine (6-OHDA), reserpine and 17-beta-oestradiol on the sensitivity of the rat anococcygeus muscle to noradrenaline (NA), acetylcholine (ACh) and KCl were investigated.2. Cocaine (10(-5)M) increased the sensitivity of the anococcygeus to NA (100-fold) but not to ACh or KCl.3. 6-OHDA treatment, whether discontinuous over 6 days or continuous for 12 days, also produced a specific increase in sensitivity to NA (50-fold).4. Reserpine ((1 mg/kg)/day) produced a small increase in sensitivity of the muscle to NA and ACh but not to KCl, after 6 days and 12 days treatment.5. 17-beta-Oestradiol (10(-5)M) had no effect on the sensitivity of the anococcygeus to NA or ACh, but reduced the sensitivity to KCl and the possible mechanism of this effect is discussed.6. Cocaine increased, while reserpine, 6-OHDA and 17-beta-oestradiol decreased, the maximum response of the muscle to KCl. The response to KCl was shown to consist of at least three components; a direct action on the muscle, an effect due to release of NA, and an inhibitory action, probably due to release of the unknown inhibitory transmitter.

Acetylcholine↗