OBJETIVE: The aim of the present work was to optimize the reaction conditions capable of generating variability and introducing systematic errors in the chain reaction of the polymerase used to analyze the gene expression for the testicular isoform of the angiotensin-converting enzyme. METHODS:The cDNA concentration, primer concentration, hybridization temperature and number of denaturation, hybridization and extension cycles were evaluated. For this purpose, samples of testis from Wistar rats fed a zinc containing diet were used to extract total RNA using the phenol-chloroform-isothiocyanate reaction. Stable cDNA was then generated by the reverse transcription reaction. Using specific primers, the gene of interest (testicular isoform of the angiotensin-converting enzyme) and the housekeeping gene for the expression of Glyceraldehyde-3-Phosphate Dehydrogenase were amplified. The samples were then submitted to gel eletrophoresis in agarose gel, stained with ethide bromide and visualized in a UV chamber. RESULTS: The results showed that the best reaction conditions for the chain reaction by the testicular isoform polymerase of the angiotensin-converting enzyme and for Glyceraldehyde-3-Phosphate Dehydrogenase were: (1) initial cDNA concentration of 2 µg, (2) primer concentration of 200nM, (3) hybridization temperature between 57.5ºC and 60.1ºC and (4) 33 cycles. CONCLUSION: It was concluded that this optimization minimized interference of the technique, contributing to the production of true, comparative data for the testicular angiotensin- converting enzyme gene expression.
diet; angiotensin-converting enzyme; gene expression; reverse transcriptase polymerase chain reaction; zinc
