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The inactivation of noradrenaline and isoprenaline in dogs
Author(s) -
GRYGLEWSKI R.,
VANE J. R.
Publication year - 1970
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1970.tb10365.x
Subject(s) - isoprenaline , phenoxybenzamine , endocrinology , medicine , chemistry , norepinephrine , hormone , propranolol , stimulation , dopamine
1 The removal of infused noradrenaline and isoprenaline from the circulation of the dog has been studied, using the blood‐bathed organ technique. 2 Both catecholamines were removed in peripheral vascular beds; in all organs studied, noradrenaline was removed to a greater degree than isoprenaline. 3 The hind legs removed an average of 60% of the noradrenaline passing through, but only 34% of the isoprenaline. With noradrenaline, the degree of removal decreased as the concentration increased, but with isoprenaline, the degree of removal increased with concentration. 4 After phenoxybenzamine, the proportion of isoprenaline removed was unchanged, whereas that of noradrenaline was decreased. The change in removal with the concentration of noradrenaline was also abolished. 5 The results are consistent with the concept that a small fraction of infused noradrenaline is removed from the circulation by Uptake 1 and that this is blocked by phenoxybenzamine. Isoprenaline, and the rest of the noradrenaline, are removed by another process (Uptake 2 ?) followed by intracellular metabolism. This inactivation process is unaffected by phenoxybenzamine in concentrations sufficient to give α‐adrenoceptor blockade. 6 After isoprenaline infusions, a substance sometimes appeared in the circulation which contracted the blood‐bathed organs. 7 The systemic pressure response to vaso‐active hormones is not a reliable indicator of the concentration of hormone in the arterial circulation.