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At least 199 records · Page 11Linked to original sources
PubMed1989

An embryonic Ca++ mobilizing muscarinic system in the chick embryo heart.

In the embryonic and in the adult heart muscarinic stimulation reduces the heart rate. Here we demonstrate that in the embryonic heart an additional muscarinic system is present, which is characterized by Ca++ mobilization and corresponds to the embryonic muscarinic system in other organ anlagen. In suspensions of embryonic chick heart cells we measured release of Ca++ from intracellular stores and influx of extracellular Ca++ with fura-2 and chlorotetracycline after muscarinic stimulation and determined the [3H]quinuclidinylbenzilate binding sites. We observed intense Ca++ mobilization at day 4, weaker reactions between day 4.5 and 11, and no Ca++ response at day 13. The pharmacological profile was identical to the profile of Ca++ mobilization in cells from other embryonic tissues in which the general embryonic muscarinic system is expressed. In parallel, we studied the effect of muscarinic agonists and antagonists on the heart rate of isolated embryonic hearts at day 4 and 5 in a perfusion chamber. Oxotremorine and bethanechol being antagonists or weak partial agonists in Ca++ mobilization, behaved as full agonists in frequency regulation. Thus, the pharmacological profile of the transient embryonic muscarinic system was different from that of the definitive adult form.

Animals↗
PubMed1990

Sensitivity and specificity of PC20 and peak expiratory flow rate in cedar asthma.

The diagnosis of red cedar asthma is usually confirmed by a specific challenge with plicatic acid, the compound responsible for the disease. We performed this study to determine the sensitivity and specificity of two other diagnostic tests, prolonged recording expiratory flow rate (PEFR) and measurement of bronchial responsiveness (provocative dose of methacholine causing a 20% fall in FEV1 [PC20 methacholine]). Twenty-three patients with suspected cedar asthma participated in the study. The patients recorded PEFR during 2 weeks away from work and 3 weeks at work. PC20 was measured both at the end of the nonworking and working period. An obvious decrease in PEFR in 2 of 3 working weeks, when PEFRs of weekends or holidays were compared (by visual inspection of the PEFR recording), and a decrease in PC20 by more than a twofold dilution, when the patient returned to work, were considered as positive tests for cedar asthma. Plicatic acid challenge test was performed at the end of the study; 14 patients reacted, whereas nine patients did not. With the results of the plicatic acid challenge test as the gold standard, the sensitivity and specificity of PEFR recordings were 86% and 89%; changes in PC20, 62% and 78%; and 93% and 45% for a positive clinical history. The combination of PEFR and clinical history revealed a 100% sensitivity with a 45% specificity. Combination of PEFR and PC20 did not improve the diagnostic accuracy.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1973

Histamine H2-receptors in the sheep bronchus and cat trachea: the action of burimamide.

Histamine-induced relaxation of the sheep bronchus was antagonized by burimamide but not by mepyramine, indicating the presence of H(2)-receptors. Mepyramine or burimamide alone produced partial antagonism of histamine-induced relaxation of the cat trachea. Both inhibitors added simultaneously effectively abolished the histamine response, suggesting that both H(1)- and H(2)-receptors are active in relaxing the cat trachea.

Animals↗
PubMed1973

Histamine H2-receptors modulate systemic anaphylaxis: a dual cardiovascular action of histamine in calves.

Depressor changes in carotid blood pressure caused by histamine or anaphylaxis in calves, were incompletely blocked by the H(1)-receptor antagonist mepyramine. Burimamide, the selective histamine H(2)-receptor antagonist, potentiated the depressor actions of histamine and anaphylaxis. Potentiated depressor responses were inhibited by mepyramine. Observations are consistent with histamine stimulating both H(1)- and H(2)-receptors to cause respectively vasodilatation and vasoconstriction.

Anaphylaxis↗
PubMed1986

11-Deoxy-11 alpha,12 alpha-methanoprostaglandin E2, a potent, short-acting bronchodilator.

11-Deoxy-11 alpha,12 alpha-methanoprostaglandin E2 (1b) and the corresponding methyl ester 7a were highly potent, but short acting, bronchodilators both by the intravenous (80 and 10 times PGE2, respectively) and aerosol (2 and approximately 1 times PGE2) routes, as measured by the Konzett-Rössler assay. The 11 beta,12 beta-methano compound 15a was two orders of magnitude less active than 7a. In rhesus monkeys anesthetized by aerosol administration, 1b was 10-50% as potent as, and had a duration of action similar to, PGE1 in the inhibition of methacholine-induced increases in airway resistance. At doses effective in preventing the methacholine response, 1b increased the heart rate (less than or equal to 30%) and precipitated mild upper airway irritation.

Aerosols↗
PubMed1976

Pharmacological assessment of 3-tert-butylsydnone.

The pharmacological effects of the mesoionic derivative, 3-tert-butylsydnone, were investigated. Administration to rats caused clonic convulsions. The CD50 of 3-tert-butylsydnone was 0.471 +/- 0.033 mmole/kg. Trimethadione, but not phenytoin sodium or proadifen hydrochloride, protected the rat from the effects of 3-tert-butylsydnone. After administration of this compound, pentobarbital sodium sleeping time was reduced in the rat, but blood pressure and ECG were unchanged in the dog. Pretreatment of the mouse with 3-tert-butylsydnone did not influence the LD50 of epinephrine hydrochloride. The action of methacholine chloride in the rat was not blocked, and the pupil of the rabbit eye was unaffected. Tests for analgesic and oxytocic activity were negative. Chronic administration of a small dose to the rat for 70 days had no effect on blood glucose, blood urea nitrogen, hemoglobin, or microhematocrit values.

Anesthesia↗