Drugs online research references
J Neurochem. 1985 Aug;45(2):407-14.
Histidine transport into rat brain synaptosomes.
Hegstrand LR, Simon JR.
Histidine transport and metabolism in rat brain synaptosomes were investigated to study the possible role of histidine uptake in the synthesis of the putative neurotransmitter histamine (HA). Histidine uptake was found to be regionally distributed and temperature sensitive, and was not totally independent of sodium or potassium ions. Transport was inhibited by metabolic inhibitors, as well as by promethazine and quinacrine. A number of other HA-related agents and several histidine metabolites had no effect. Kinetic analyses of histidine transport revealed the presence of both high- and low-affinity systems in cerebral cortex. Histidine uptake increased following preexposure of synaptosomes to depolarizing concentrations of potassium. This effect was dependent on the presence of calcium ions during the preincubation. No newly formed [3H]HA was detectable in rat brain synaptosomes following [3H]histidine transport. Lesions of the medial forebrain bundle did not alter histidine uptake in the hippocampus or cerebral cortex. Ontogenic studies indicated that the histidine uptake system developed rapidly and reached a peak during postnatal days 12-17. Overall, the present findings do not support a role for histidine transport in the regulation or maintenance of neurotransmitter pools of HA in rat brain.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3874263&dopt=Abstract
Am J Hosp Pharm. 1982 Mar;39(3):460-7.
Interactions between drugs and intravenous delivery systems.
Kowaluk EA, Roberts MS, Polack AE.
The loss of 45 drugs from intravenous solutions during simulated infusions through plastic infusion sets; factors affecting such losses; and ways to minimize these losses are investigated. A total of 43 drugs was studied in 0.9% sodium chloride solution; one drug was in 5% dextrose solution and one in a solvent supplied by the manufacturer. Drug loss was studied in plastic infusion sets, with and without burette chambers, and glass infusion bottles; polyethylene and silastic tubing with glass syringes on an infusion pump; and single-use all-plastic syringes. Variables studied were flow rates, infusion times, drug concentrations, pH, and tubing lengths and radii. Clomethiazole edisylate, chlorpromazine hydrochloride, diazepam, promazine hydrochloride, promethazine hydrochloride, thiopental sodium, thioridazine hydrochloride, and trifluoperazine dihydrochloride were lost from solution during infusions through at least one system. The loss of most drugs during infusion was slow, time-dependent, and concentration-independent, indicating a diffusion-controlled sorption process rather than a binding, adsorptive process. Drug loss was lowest in short lengths small-diameter tubing with low permeability constants. None of the drugs was lost stored in all-plastic single-use syringes. It is concluded that loss of drugs through sorption processes can be minimized by administering infusions through short lengths of small-diameter tubing made of inert plastics.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7072732&dopt=Abstract
Dev Pharmacol Ther. 1981;2(3):180-7.
Comparative effects of age and sedation on sinus node automaticity and atrioventricular conduction.
Clapp S, Driscoll DJ, Mitrani I, Lewis RM, Gillette PC.
Corrected sinus node recovery time (CSNRT) and atrioventricular node effective refractory period are longer in nonsedated adults than in sedated children at cardiac catheterization. We attempted to ascertain the relative contributions of age and catheterization sedation on these differences by studying adult beagles and beagle puppies previously instrumented with atrial pacing wires. We found that CSNRT was similar in adults and puppies prior to drug administration. CSNRT shortened significantly after meperidine, promethazine, and chlorpromazine (DPT) administration in both adult dogs and puppies. Atrioventricular node effective refractory period (AVERP) was shorter in puppies than adults prior to DPT, and did not shorten in in either group after DPT. These findings suggest that the difference between CSNRTs in children and adults can be at least partly explained by the sedation used in children. This is an important consideration when premedicating children for electrophysiologic studies, particularly in children with suspected sinus node dysfunction.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7227143&dopt=Abstract
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