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Vasoactive properties of phenylpropanolamine (d, I‐norephedrine) and its enantiomers in isolated rat caudal artery
Author(s) -
Johnson David A.,
Maher Timothy J.
Publication year - 1991
Publication title -
drug development research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.582
H-Index - 60
eISSN - 1098-2299
pISSN - 0272-4391
DOI - 10.1002/ddr.430230207
Subject(s) - chemistry , potency , perfusion , vasoconstriction , phenylpropanolamine , reserpine , enantiomer , stimulation , endocrinology , nifedipine , medicine , artery , pharmacology , calcium , stereochemistry , in vitro , chromatography , biochemistry , organic chemistry
The sympathomimetic properties of PPA and its individual component enantiomers d‐ and l‐norephedrine (NOR) were examined in isolated perfused/superfused caudal arteries from Sprague‐Dawley (SD) rats. Segments of caudal artery were cannulated, mounted in a tissue bath, and perfused with a modified Kreb's solution. PPA, d‐ and I‐NOR were alternately injected into the perfusion stream, and vasoconstriction was measured as the rise in perfusion pressure. Various drugs were added to the perfusion buffer to determine the activity of PPA, d‐, and I‐NOR at specific adrenoceptor subtypes and to determine whether the actions of these vasoconstrictors were influenced by calcium channel antagonists, cocaine, or reserpine. The results demonstrated that the norephedrines acted as partial agonists primarily via direct stimulation of postjunctional alpha 1 ‐adrenoceptors with relatively low potency; however, I‐NOR did have significant activity at beta‐adrenoceptors with relatively low potency; however, I‐NOR did have significant activity at beta‐adrenoceptors as well. When the enantiomers of PPA were compared, d‐NOR had only minor vasoconstrictor activity, relative to I‐NOR, which was well over 100 times less potent than the endogenous.