RESUMO
OBJECTIVE: This study aimed to determine the effect of parathyroid hormone-related protein (PTHrP) on proliferation of cardiac fibroblasts (CFs) in primary cultures of neonatal Wistar rats. METHODS: Different PTHrP concentrations were added to CFs of neonatal Wistar rats and the cells were grouped according to the concentrations added. A verapamil (VPL) group and a calcitriol (CAL) group were also established. Changes in cell proliferation and in cyclic adenosine monophosphate and calcium ion levels were identified and recorded. RESULTS: We found that as the concentration of PTHrP increased, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT, a tetrazolium salt) colorimetric absorbance values (A values) decreased. These values in the PTHrP groups were significantly lower than those in the control group. MTT colorimetric A values and 3H-thymidine deoxyribose intake were lower in the VPL group, low-dose CAL group, and the PTHrP 10-7 mol/L group compared with the control group. However, MTT colorimetric A values and 3H-thymidine deoxyribose intake were higher in the high-dose CAL group than in the PTHrP 10-7 mol/L group. As PTHrP concentrations increased, intracellular cyclic adenosine monophosphate concentrations also increased. CONCLUSION: PTHrp, VPL, and low-dose CAL inhibit proliferation of CFs, while high-dose CAL promotes proliferation of CFs.