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M Bellemare

Publications and source records attributed to M Bellemare.

5 recordsLinked to original sources
PubMedDate not supplied

The effect of LSD on the histology and ultrastructure of the neuroepithelium of young chick embryos: a stereological study.

Five control chick embryos and fifteen exposed to LSD at concentrations of 2.5, 12.5 and 50 mug/ml were examined. The morphometric analysis performed at the light microscope level shows that (1) the section area of the neural tube increases with the two highest doses of lysergic acid diethylamide (LDS) employed, (2) the volume fraction of the intercellular spaces decreases with the two highest doses of LSD, (3) the volume fraction of the nuclei in the neural tube is not modified with any concentrations of LSD employed, (4) the volume fraction of the cytoplasm in the neural tube increases with all three concentrations, and (5) the nucleo-cytoplasmic ratio decreases with all three doses employed. Moreover, at the ultrastructural level, it was found that (1) the volume fraction of mitochondria in the cytoplasm decreases at doses of 12.5 and 50 mug/ml (2) the surface to volume ratio of the mitochondria is unchanged with any of the concentrations of LSD employed and (3) the surface density of the endoplasmic reticulum in the cytoplasm increases only with a dose of 2.5 mug/ml of LSD.

Animals↗
PubMedDate not supplied

Role of the endopeptidase 24.11 in the disposition and metabolism of endogenous atrial natriuretic factor in the rabbit.

The neutral endopeptidase 24.11 (NEP) has been shown to inactivate the atrial natriuretic factor (ANF) by opening the ring structure. To document the role of NEP in the metabolic fate of ANF in vivo, the effects of an infusion of thiorphan (25 micrograms/min/kg), a specific NEP inhibitor, on the kinetics and metabolism of endogenous ANF were studied in conscious rabbits. A bolus of [125I]ANF(99-126) was injected 50 min after the beginning of the infusion of thiorphan. Plasma samples containing the radioactive peptides were separated by reverse-phase HPLC. The parent compound could be separated from at least two other minor metabolites, corresponding to the elution position of [125I]ANF(99-105/106-126), the inactive ring-opened metabolite, and of [125I]ANF(103-126), an N-truncated analog. The generation of the N-truncated metabolite was increased by thiorphan. Thiorphan also induced an increase in plasma ANF (29%) that was closely associated with a 32% reduction in the systemic clearance of [125I]ANF(99-126), whereas no modification in the estimated secretion rate was detected. These results support a role for NEP in the regulation of endogenous ANF plasma levels. These results also suggest that specific inhibition of NEP may result in an increase in the apparent activity of alternative metabolic pathways.

Animals↗