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Biomedical subjects

H Ladinsky

Publications and source records attributed to H Ladinsky.

103 records · Page 6Linked to original sources
PubMed1972

A quantitative study of the anticholinergic action of several tricyclic antidepressants on the rat isolated fundal strip.

1. Investigations were carried out on the antagonism of the action of carbamylcholine chloride on the isolated fundus of the rat stomach by several tricyclic antidepressants.2. The anticholinergic potency of the compounds was in the order: GP 45437>amitriptyline>protriptyline>desmethylimipramine>opipramol. All of the antagonists were less effective than atropine.3. Statistical analysis was carried out to determine whether the theory of competitive antagonism would fit the data obtained.

Amitriptyline↗
PubMed1972

Effect of chemical sympathectomy on the content of acetylcholine, choline and choline acetyltransferase activity in the cat spleen and iris.

1. Acetylcholine and choline were measured in the spleens and irides of normal and 6-hydroxydopamine-treated cats. In addition, choline acetyltransferase activity was measured in the spleens.2. No acetylcholine or choline acetyltransferase activity were found in spleens of normal or treated cats. The choline content of normal spleens was 12.4 +/- 1.5 mug/g wet wt. (mean +/- S.E. of mean), which was not significantly altered by chemical sympathectomy.3. The acetylcholine and choline contents of the cat iris were 3.0 +/- 0.3 mug/g wet wt. and 7.7 +/- 0.9 mug/g wet wt., respectively. There was no difference in acetylcholine and choline concentrations between left and right or normal and sympathectomized irides.4. These results are discussed in relation to the question of a cholinergic link in post-ganglionic sympathetic transmission.

Acetylcholine↗
PubMed1966

Studies on the in vitro interaction of electrical stimulation and Ca++ movement in sarcoplasmic reticulum.

Sarcoplasmic reticulum fragments (S.R.F.) were isolated from skeletal and heart muscles. These fragments were found to take up Ca(++) very actively from media. When monophasic square waves were passed through the S.R.F. suspension, the Ca(++) uptake by S.R.F. was decreased. When the suspension was stimulated electrically after the Ca(++) was taken up by S.R.F., the initiation and the cessation of the stimulation were followed by the release and re-uptake of Ca(++) by S.R.F., respectively. The degree of inhibition of the Ca(++) uptake as well as of the Ca(++) release by electrical stimulation was dependent on the voltage and the frequency of stimulation. The presence of inorganic phosphate or oxalate modified the influence of electrical stimulation on the release and the uptake of Ca(++) by S.R.F. Attempts were made to observe the release of Ca(++) by electrical stimulation from unfractionated sarcoplasmic reticulum remaining in myofibers, and the interaction of the released Ca(++) with myofibrils in vitro. For this purpose, the glycerol-extracted fiber was selected as a muscle model, since it contains both sarcoplasmic reticulum and myofibrils. It was found that electrical stimulation of skeletal and heart glycerol-extracted fibers resulted in the contraction of fibers. It appeared that the contraction of glycerol fibers by electrical stimulation was caused by the Ca(++) release from sarcoplasmic reticulum by stimulation.

Adenosine Triphosphate↗
PubMedDate not supplied

Decrease in rat striatal acetylcholine levels by some direct- and indirect-acting dopaminergic antagonists.

Several direct- or indirect-acting dopamine receptor antagonists were found to decrease rat striatal acetylcholine levels. The maximum decrease of about 50% was produced by pimozide (0.5 mg/kg), by haloperidol (0.5 mg/kg) and by reserpine (2.5 mg/kg). The decreases in acetylcholine produced by pimozide and by haloperidol were found to be specific for the striatum and did not alter diencephalonic, mesencephalonic, cerebellar or hemispheric acetylcholine levels. Furthermore, these two drugs completely blocked the increase in striatal acetylcholine produced by the dopamine receptor agonist, apomorphine, and had no effect on striatal choline acetyltransferase and cholinesterase. These data suggest that haloperidol and pimozide act on the striatal cholinergic neurons through strong blockade of dopamine receptors. Reserpine presumably decreased striatal acetylcholine levels indirectly by depleting biogenic amines. Clozapine and 1-fenfluramine were unable to block the action of apomorphine, as was shown previously for chlorpromazine. It is thus suggested that these drugs are reversible dopamine receptor antagonists. Their weaker action in decreasing striatal acetylcholine may depend upon this property.

Acetylcholine↗
PubMedDate not supplied

Identification of serotonin 5-HT4 recognition sites in the porcine caudate nucleus by radioligand binding.

Specific binding for the serotonin 5-HT4 receptor (5-HT4R) radioligand [3H]GR 113808 was identified in pig caudate nucleus and characterized by serotonin subtype selective drugs. Binding was inhibited by serotonin and by synthetic indoles, benzamides and benzimidazolones known to characterize the 5-HT4R in functional tests. Rank order of potency of 5-HT4R antagonists was: GR 125487 (Ki, 0.19 nM) > GR 113808 >> SC 53606 > SDZ 205,557 > RS 235971/190 > DAU 6285 > tropisetron > DAU 6215. GR 125487 and GR 113808 were highly selective with respect to the 5-HT3 receptor (5-HT3R). Rank order of potency of 5-HT4R agonists was: SC 53116 (Ki, 21 nM) > BIMU 1 > cisapride > BIMU 8 > serotonin > renzapride > S-zacopride > metoclopramide > R-zacopride > 5-methoxytryptamine >> 5-carboxamidotryptamine. BIMU 8, renzapride, metoclopramide and the zacopride enantiomers gave shallow competition curves. The agonists were substantially less selective than the antagonists with respect to the 5-HT3R. With only two exceptions, SCH 23390 and metergoline, which bound with sub-microM affinity to the 5-HT4R, binding was not inhibited by compounds selective for other G-protein-coupled or channel-gated receptors. Highly significant correlations in affinities of compounds for 5-HT4R in caudata of pigs, guinea pigs and humans were found suggesting no difference among mammalian species.

Animals↗