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Biomedical subjects

F F Foldes

Publications and source records attributed to F F Foldes.

At least 73 records · Page 4Linked to original sources
PubMed1975

The effects of protoveratrine and germines on the release of acetylcholine from the Auerbach plexus of the guinea-pig ileum.

The effect of protoveratrine A and germine-3-acetate (GMA) on the release mechanism of acetylcholine from the nerve terminals of the Auerbach plexus in the longitudinal muscle layer of the guinea-pig ileum was studied. Protoveratrine A, GMA and germine potentiated neuroeffector transmission in Auerbach's plexus in the longitudinal muscle preparation provided the neurons were stimulated at low frequencies (less than 10 Hz). Protoveratrine A and GMA enhanced the release of acetylcholine from the nerve terminals during the resting period and at low frequency of stimulation (less than 10 Hz). At continous stimulation with high frequency they were ineffective (greater than 10 Hz). When trains of 20 stimuli, with a pulse interval of 0.1 s (10 Hz) were repeatedly applied with intervals of 0.1 to 20 s between trains, the effect of GMA to increase ACh release depended on the length of the train interval; the longer the resting period between trains the higher was the output of ACh. This fact indicates that the release of ACh increased primarily during the resting periods following single stimuli or trains. The effect of GMA on ACh release proved to be highly temperature-dependent: in the presence of GMA Q10 increasing from 3.25 to 4.92. A high Ca concentration, removal of Mg or lowering of the Na concentration abolished the effect of GMA to enhance ACh release.

Acetylcholine↗
PubMed1975

Preparation and evaluation of a sustained naloxone delivery system in rats.

The use of a non-biodegradable polymer system to provide a sustained release of the narcotic antagonist naloxone in rats is described. The kinetics of morphine analgesia (measured by the hot-plate test) in the presence of the naloxone implant, and the urinary excretion of radiolabeled naloxone were measured. The shift of the morphine dose-response curve to the right is expressed in terms of dose ratios, which were calculated from the ED50 values for morphine obtained 9 days before, and 1, 8, 15, 22 and 29 days after implantation of the polymer. Our experiments indicate that effective levels of antagonist were maintained for 3-4 weeks after implantation of a polymer system containing 16 mg of naloxone. After 29 days, more than 95% of the absorbed drug had been released, with 16% of the implanted radioactivity appearing in the urine. These results demonstrate the feasibility of using a sustained release form of a narcotic antagonist to block the effects of morphine.

Animals↗
PubMed1975

Ocular absorption of naloxone in narcotic addicts.

Naloxone hydrochloride was administered by regional intravenous injection (three patients) or by instillation into the conjunctival sac (10 patients) in addicts receiving methadone maintenance. After the regional intravenous administration of 100 mug naloxone,no withdrawal symptoms occurred on release of the occluding tourniquets, nor were theresignificant changes in electrical skin resistance or sweating in the upper extremities. On the other hand, the conjunctival instillation of 2 to 3 mg naloxone produced withdrawal symptoms in five patients and frequently also caused pupillary dilatation whichwas usually equal on both sides.

Absorption↗
PubMed1975

Plasma and red cell cholinesterase activity in uremic patterns (effects of hemodialysis and renal transplantation).

Plasma butyrylcholinesterase (BuChE) and red cell acetylcholinesterase (AChE) activity was measured in patients with endstage kidney disease undergoing hemodialysis or renal transplantation. All patients had significantly lower values of BuChE activity than normals. A single hemodialysis did not influence the level of BuChE activity but caused a moderate, though statistically significant increase of red cell AChE activity. Chronic hemodialysis significantly increased BuChE but did not affect AChE activity. After successful renal transplantation a sharp fall of BuChE activity occurred, a completely unexpected finding. This decrease coincided with the administration of large doses of glucocorticoids. Once the dose of these drugs was decreased the activity of plasma BuChE returned toward preoperative values. No similar changes in red cell AChE were seen. The possible effect of the steroid drugs on protein synthesis in the liver is discussed.

Acetylcholine↗