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Biomedical subjects

L DeRoth

Publications and source records attributed to L DeRoth.

30 records · Page 2Linked to original sources
PubMed1979

Relaxant response of goat trachea to 5-hydroxy-tryptamine mediated by D-tryptamine receptors.

1 Goat isolated trachea contracted in response to carbachol, histamine and 2-pyridylethylamine (an H(1)-receptor agonist) and relaxed after application of isoprenaline. 5-hydroxytryptamine (5-HT) and phenylephrine.2 Mepyramine, a selective H(1)-receptor antagonist, blocked histamine- and 2-pyridylethylamine-induced contractions. In high doses it also exhibited some nonspecific antagonism to carbachol. After H(1)-receptor blockade, 4-methylhistamine and dimaprit (specific H(2)-agonists) relaxed the carbachol-contracted trachea.3 Propranolol, a beta-adrenoceptor blocker, antagonized relaxation in response to isoprenaline and phenylephrine. In high doses, it produced a reversal of the phenylephrine response.4 Indomethacin enhanced contractions in response to carbachol and histamine.5 Relaxation to 5-HT was not affected by propranolol, indomethacin, metiamide or cimetidine (H(2)-blockers). These findings appear to exclude the involvement of adrenergic, prostaglandinergic and H(2)-histaminergic mechanisms in the mediation of this response.6 Atropine potentiated 5-HT-induced relaxations. This suggests the participation of a ;masked' excitatory cholinergic mechanism.7 Methysergide, dibenamine and dibenzyline selectively antagonized or reversed 5-HT-induced relaxation. Dibenamine and dibenzyline enhanced relaxations to isoprenaline.8 This investigation showed (i) a relaxant response of goat trachea to 5-HT, mediated via D-muscular tryptamine receptors; (ii) a small population of excitatory M-neuronal tryptamine and alpha-adrenoceptors; and (iii) predominance of H(1)-histamine receptors in the goat trachea.

Animals↗
PubMed1979

Dual histamine receptor mechanism in guinea-pig lung.

Isolated guinea-pig lung parenchymal strips (GPLS) relaxed in response to the selective histamine H2-receptor agonists, dimaprit and 4-methylhistamine (4-MeH), and to low doses of histamine (10(-9) to 10(-7) mol/l) and contracted in response to several spasmogens. The order of the relative activity of the spasmogens was 2-methylhistamine (2-MeH) greater than histamine greater than carbachol greater than 2-pyridylethylamine (2-PE). Dimaprit and 4-MeH also relaxed GPLS which were contracted by 2-MeH, 2-PE or carbachol. Metiamide (a selective H2-antagonist: 5 x 10(-5) mol/l inhibited or reversed relaxations to histamine, dimaprit and 4-MeH, and significantly enhanced contractile responses to histamine without altering responses to carbachol. Mepyramine (a selective H1-receptor antagonist: 10(-8) to 10(-6) mol/l antagonized histamine-induced contractions. This investigation shows: (1) histamine is more active than carbachol in GPLS and (2) the occurrence of histamine H1-receptors mediating contraction and H2-receptors mediating relaxation in guinea-pig lung.

Animals↗
PubMed1979

Determination of body surface area in neonatal swine.

The body surface area of 30 neonatal pigs of both sexes, weighing 445--1,976 g, were determined by the direct skinning technique. The range of measured body surface area values was 635--1,400 cm2 (mean = 895.1 cm2). The regression line, fitted to a scatter diagram and calculated by the least square method, was found to be Y = 337.2 + 0.553X; where X was body weight expressed in grams and Y was body surface area expressed in square centimeters.

Animals↗
PubMed1979

Relaxant action of histamine on rabbit trachea: possible existence of third histamine receptor subtype.

The carbachol contracted rabbit trachea relaxes to isoproterenol, PGE1, E2, histamine and bradykinin. Histamine-induced relaxations were resistant to mepyramine (an H1-antagonist), burimamide, cimetidine, metiamide (H2-antagonists), propranolol (a beta-adrenoceptor blocker), indomethacin (a potent inhibitor of prostaglandin synthesis), trasylol (an inhibitor of kallikreins), aminophylline (a purinergic receptor blocker) and dibenzyline (a "D"-tryptamine receptor antagonist). The evidence achieved with these pharmacological agents appears to suggest that the chemical mediator responsible for the relaxant response to histamine is unlikely to be: catecholamines, prostaglandins, 5-HT, adenosine or ATP or kinins. The existence of H2-(iso or H3) histamine receptor subtype in rabbit trachea is postulated.

Airway Resistance↗
PubMed1979

Pharmacological characterization of the rabbit lung strip.

Isolated rabbit lung parenchymal strips contracted to epinephrine (E), norepinephrine (NE), phenylephrine (PE), histamine, carbachol, PGF2alpha, bradykinin and 5-HT. Lung strips which were maximally contracted to histamine, carbachol and PGF2alpha, relaxed to isoproterenol, salbutamol, terbutaline and PGE1 however, they exhibited superimposed contractions to E, NE and PE. Atropine and mepyramine selectively antagonized contractions to carbachol and histamine respectively, without modifying contractions to the sympathomimetic agents. Phenotolamine antagonized responses to E, NE and PE. The results of this investigation suggest the presence of alpha- and beta-adrenergic and H1-histamine receptors in the rabbit lung strip.

Airway Resistance↗
PubMed1979

Pharmacological study of bovine airways. Evidence for excitatory and inhibitory effects of histamine.

Bovine airway muscle contracts to carbachol greater than histamine greater than 2-methylhistamine greater than prostaglandin F2 alpha. Trachea of neonatal calves are more sensitive to histamine than those of older cattle. Partially contracted bovine airways relax to prostaglandins E1 and E2 greater than dopamine greater than phenylephrine greater than 4-methylhistamine greater than dimaprit. Histamine-induced airway constriction was incompletely blocked by mepyramine and the mepyramine-resistant component was blocked by atropine. After H1-receptor blockade, histamine-induced tracheobronchial relaxation was incompletely antagonized by metiamide and not blocked by propranolol or indomethacine, suggesting an atypical histamine receptor not associated with catecholamine or prostaglandin production.

Age Factors↗
PubMed1978

Basic cardiovascular parameters in the underweight neonatal swine.

Some hematological and cardiovascular parameters of the underweight neonatal piglets have been compared with normal-weight 1 and 7-day-old swine (Sus scrofa domestica). The underweight swine had a significantly lower leukocyte count, plasma protein level and blood glucose level, but a significantly higher plasma LDH level. Heart rate and arterial blood pressure were significantly lower in the underweight group. Based on the observed results it was postulated that the piglets born with a low body weight could also be physiologically immature since the cardiovascular parameters measured approximated those reported for normal fetuses of the same weight. Further studies are required to ascertain if a functional immaturity persists in the neonatal animals.

Animals↗