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Biomedical subjects

R W Foster

Publications and source records attributed to R W Foster.

At least 91 records · Page 5Linked to original sources
PubMed1975

Evidence that adrenergic nerves are responsible for the active uptake of noradrenaline in the guinea-pig isolated trachea.

1 6-Hydroxydopamine (50 mg/kg, i.p.) was given to guinea-pigs to destroy the adrenergic nerve terminals in the trachea. 2 The destruction was demonstrated by fluorescence histochemistry, which showed a marked loss of beaded fluorescent terminal fibres and by electrical transmural stimulation of the isolated atropinized trachea, which showed a marked reduction of dilator responses. 3 Such tracheae showed greatly reduced uptake-with-retention of (minus)-[3H]-noradrenaline in incubation experiments and the efflux curve of radioactive material showed a selective but incomplete reduction in the volume of the slowly exchanging compartment. 4 It is concluded that much, but perhaps not all, of the uptake-with-retention occurs into adrenergic nerves.

Animals↗
PubMed1972

Some evidence of the active uptake of noradrenaline in the guinea-pig isolated trachea.

1. Guinea-pig isolated trachea immersed in a low concentration (50 nM) of (-)-(3)H-noradrenaline accumulates radioactive material against an apparent concentration gradient.2. Compartmental analysis based on the decay curve of radioactive material content during washout and its comparison with that of (14)C-sorbitol shows that some extracellular noradrenaline is adsorbed. A considerable mass exists in a slowly exchanging compartment, i.e. is retained. This retention is inversely concentration dependent.3. Over a 25-fold range of concentration the entry of either total radioactive material or noradrenaline followed Michaelis-Menten kinetics.4. The uptake of radioactive material was sodium-dependent and ouabain-sensitive.5. The uptake was susceptible to metabolic poisons which deprive the tissue of all available energy but it was not exclusively associated with either oxidative or glycolytic energy supply.6. Although net uptake could not be distinguished from exchange with endogenous amine, other evidence has been obtained for an active noradrenaline transport system with properties similar to neuronal uptake.

Animals↗
PubMed1969

An uptake of radioactivity from (plus or minus)-3H-isoprenaline and its inhibition by drugs which potentiate the responses to (minus)-isoprenaline in the guinea-pig isolated trachea.

1. The uptake of radioactivity derived from (+/-)-(3)H-isoprenaline by the guinea-pig isolated trachea has been measured, and the assumption is made that all the radioactivity is due to isoprenaline.2. 40% of the total (+/-)-(3)H-isoprenaline taken up was loosely bound to the tissue while 25% was firmly bound.3. The firmly bound component of the uptake was more susceptible to inhibition by drugs than the loosely bound component.4. Desipramine and cocaine did not reduce the accumulation of firmly bound isoprenaline.5. Cooling to 23 degrees C, guanethidine and phentolamine caused a moderate reduction in the accumulation of firmly bound isoprenaline.6. Phenoxybenzamine and (+/-)-metanephrine caused a highly significant reduction in the accumulation of firmly bound isoprenaline.7. These findings are discussed in relation to previous studies of the uptake of isoprenaline and of other processes which may be related.8. The inhibition of uptake by the agents examined correlated with their potentiation of the action of (-)-isoprenaline found previously.9. It is suggested that a tissue uptake can significantly modify the pharmacological response to isoprenaline in vitro.

Animals↗