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Biomedical subjects

D A Cook

Publications and source records attributed to D A Cook.

At least 127 records · Page 7Linked to original sources
PubMed1980

N,N-Diethyl-2-(1-pyridyl)ethylamine, a partial agonist for the histamine receptor in guinea pig ileum.

N,N-Diethyl-2-(1-pyridyl)ethylamine (E-2-P) produced 59 +/- 7% of the maximal response to histamine in guinea pig ileal longitudinal smooth muscle and antagonized the responses of this tissue to histamine. The estimated binding constant of E-2-P for the histamine receptor predicted a binding curve nearly coincident with the agonist concentration-response curve indicating no receptor reserve for this partial agonist. Diphenhydramine (30 nM) produced competitive antagonism of response to E-2-P (pKB = 8.3 +/- 0.13). Triprolidine (0.3 nM), a slower acting antihistamine, produced a depression of the maximal responses to E-2-P. This effect was analyzed in terms of a "hemi-equilibrium" hypothesis which approximates a pseudoirreversible antagonism of histamine receptors by triprolidine with respect to E-2-P. All data are consistent with the classification of E-2-P as a simple partial agonist for the histamine receptor of guinea pig ileum.

Animals↗
PubMed1980

The use of a contract admission procedure on an acute psychiatric admission ward.

The patients discharged from a 24 bed acute psychiatric admission ward over a six-month period after the introduction of a contract admission procedure were compared with a similar group, discharged over the identical six-month period of the preceding year, before the use of the new procedure. The length of stay in hospital was found to be reduced, but preliminary studies suggest that the readmission rate is not significantly altered. There was no evidence to suggest that shortening the length of stay in hospital increased the likelihood of relapse, nor were increased demands made on the day hospital service.

Acute Disease↗
PubMed1978

Responses of rabbit portal vein to histamine.

1 Histamine produced a dose-dependent contraction of the isolated portal vein of the rabbit. This contraction was not antagonized by atropine, methysergide, indomethacin, cocaine or 6-hydroxy-dopamine, nor by pretreatment of the rabbit with reserpine. 2 The response to histamine was blocked by H1-receptor antagonists only when the blocking agent was used in very high concentrations, and was not antagonized by the H2-receptor blocking agent, metiamide, H1-receptor antagonists did not block the effects of 5-hydroxytryptamine. 3 The contractions elicited by histamine, 5-hydroxytryptamine and noradrenaline were blocked by phentolamine. 4 Desensitization to high doses of 5-hydroxytryptamine caused a concomitant depression in the response to histamine but not to noradrenaline or acetylcholine. 5 The results suggest that the contractions of rabbit portal vein elicited by histamine are not mediated by receptors of the H1- or the H2-type, but may involve an action of histamine at a receptor which is also involved in the action of 5-hydroxytryptamine.

Animals↗
PubMed1978

Resistance of the histamine H2 receptor in guinea-pig heart to blockade by phenoxybenzamine.

Phenoxybenzamine is a potent irreversible H1 receptor antagonist in a variety of tissues. In order to assess the ability of this agent to antagonise the H2-receptor, we have examined the effects of phenoxybenzamine on the histamine-induced positive inotropic effect in electrically driven strips of guinea-pig right ventricle. Even at concentrations as high as 10(-4)M no significant change in the responses to histamine was observed. It is concluded that the histamine H2 receptor is unexpectedly resistant to antagonism by 2-haloalkylamines.

Animals↗
PubMed1976

Blockade of histamine-induced contractions of guinea pig ielum by beta-haloalkylamines.

In the longitudinal muscle strip of guinea pig ileum phenoxybenzamine (POB) produces a maximum parallel shift of 0.7 log units in the dose-response curve to histamine. In the presence of sodium thiosulfate in the wash fluid the parallel shift whith retention of maximum response increases to about 2 log units, and a similar value is obtained for Nethyl-N-(2-bromoethyl)-1-naphthylamine. The The agent N-ethyl-N- (2-chloroethyl)benzylamine produces a significantly smaller shift of dose-response curve of 1.53 log units before the maximum response becomes depressed. The receptor-specific depression of maximum response produced by higher doses of POB is reversed by sodium thiosulfate and by bovine serum albumin, while the parallel shift in dose-response curve is unaffected by both treatments. These findings may be explained by a hypothesis involving interaction of 2-haloalkylamines at two sites.

Amines↗
PubMed1976

The protective effects of methysergide, 6-hydroxydopamine and other agents on the toxicity of amphetamine, phentermine, MDA, PMA, and STP in mice.

The ability of various drugs to prevent the lethal effects of 4-methoxyamphetamine (PMA) and 3, 4-methylenedioxyamphetamine (MDA) were reduced by pretreatment with phentolamine and 6-hydroxydopamine suggesting that release of norepinephrine from peripheral adrenergic nerves contributed to their toxicity. Pretreatment with methysergide reduced the lethal effects of (+)- and (-)-amphetamine, MDA, PMA and 2, 5-dimethoxy-4-methylamphetamine (STP) suggesting that an action on serotonergic receptors contributed to their toxicity. Pretreatment with 4-chloroamphetamine, practolol and haloperidol did not alter the lethal effects of the agents studied.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1975

Thermal alterations in onset and offset rate constants for chlorpheniramine.

The onset and offset rate constants for chlorpheniramine were obtained using the longitudinal muscle of guinea pig ileum. Between 21 degrees C and 37 degrees C these values follwed linear Arrhenius plots with activation energies similar to other biological systems. Below 18 degrees C the nature of the antagonism changed prohibiting estimation of the rate constants. It is concluded that at higher temperatures the histamine receptor behaves in a uniform manner, but below 20 degrees C a change in properties occurs.

Animals↗