REGIONAL DIFFERENCES IN EXTRACELLULAR PURINE DEGRADATION IN THE PROSTATIC AND EPIDIDYMAL PORTIONS OF THE RAT VAS DEFERENS
1. The aim of the present study was to compare ecto-nucleotidase activities in rat bisected vas deferens using 1,N6-etheno(ε)-nucleotides (ε-ATP and ε-AMP) as substrates. Degradation was estimated by measuring the disappearance of the substrate and the appearance of its metabolites using HPLC with fluorescence detection. Incubation of tissue preparations (prostatic or epididymal portions) with 300 nmol/L ε-ATP at 37°C caused a partial disappearance of ε-ATP and appearance of its metabolites (ε-ADP, ε-AMP and ε-adenosine). Incubation at 25°C reduced ε-ATP degradation more in the prostatic than in the epididymal portion.
2. Incubation of tissue preparations with ε-AMP at 37°C resulted in the disappearance of ε-AMP and the appearance of ε-adenosine, which was more pronounced in the epididymal than in the prostatic portion. Incubation at 25°C reduced ε-AMP degradation more in the epididymal than in the prostatic portion.
3. Decreasing pH from 7.4 to 6.5 enhanced ε-AMP degradation only in the prostatic portion, whereas increasing pH from 7.4 to 8.5 enhanced ε-AMP degradation in both portions, but more markedly in the epididymal portion. The alkaline phosphatase inhibitors levamisole (10 mmol/L) and β-glycerophosphate (10 mmol/L) reduced ε-AMP degradation only in the epididymal portion.
4. In conclusion, the results of the present study are compatible with the presence, in the bisected rat vas deferens, of an ecto-nucleotidase system that is involved in the degradation of extracellular purines, which may differ between the epididymal and prostatic portions, with the epididymal portion presenting a different and higher capacity to form adenosine.
Document Type: Original Article
Affiliations: Laboratório de Farmacologia, Centro de Estudos de Química Orgânica, Fitoquímica e Farmacologia da Universidade do Porto, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, Porto, Portugal
Publication date: September 1, 2005