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FORMATION OF DOPAMINE AND NORADRENALINE IN RAT VAS DEFERENS: COMPARISON WITH GUINEA‐PIG VAS DEFERENS
Author(s) -
BOADLEBIBER MARGARET C.,
ROTH R.H.
Publication year - 1975
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.1476-5381.1975.tb07613.x
Subject(s) - vas deferens , dopamine , medicine , endocrinology , chemistry , catecholamine , guinea pig , incubation , norepinephrine , biology , biochemistry
1 The formation of [ 14 C]‐3,4‐dihydroxyphenylalanine (DOPA) from [ 14 C]‐tyrosine, in the presence of the amino acid decarboxylase inhibitor, brocresine (3‐hydroxy‐4‐bromobenzyloxy‐amine dihydrogen phosphate), was greatly enhanced in rat vasa deferentia depolarized by a KCl‐enriched Krebs‐Henseleit solution (52 mM KCl) compared with tissues maintained in unmodified Krebs‐Henseleit solution. 2 When the conversion of tyrosine was allowed to proceed as far as catecholamine (brocresine absent) no significant difference was observed between the accumulation of [ 14 C]‐catecholamines (CA) in depolarized rat vasa deferentia and the accumulation in control (non‐depolarized) tissues. 3 Endogenous CA levels in the depolarized rat vasa deferentia fell to 67% of the controls after a 1 h incubation period and to 53% at the end of 2 hours. 4 Chromatographic separation on Amberlite CG‐120 columns of the newly synthesized CA and catechol metabolites from the rat vas deferens revealed that a very high proportion was present as dopamine. The percentage distribution after 1 h incubation in control Krebs‐Henseleit was: noradrenaline (NA): 30.6 ± 5.2; dopamine 56.9 ± 5.9; acid metabolites: 12.8 ± 1.1; and in KCl‐rich Krebs‐Henseleit, NA: 32; dopamine: 44.7 and acid metabolites 23.3. In contrast to the newly synthesized ( 14 C‐labelled) CA, endogenous dopamine comprises only 10% of the endogenous CA stores in rat vas deferens. 5 The distribution of newly synthesized NA and dopamine in rat vas deferens is strikingly different from that of guinea‐pig vas deferens where more than 80% of newly formed amine is present as NA. In the latter tissue depolarization with K + causes a striking increase in CA biosynthesis.