Effects of arginine vasopressin on inducible nitric oxide synthase-nitric oxide system activity in cultured rat cardiac fibroblasts

Objective To explore the effects of arginine vasopressin (AVP) on inducible nitric oxide synthase (iNOS) nitric oxide (NO) system activity in cultured rat cardiac fibroblasts. Methods Cardiac fibroblasts were isolated by trypsin digestion method. Nitric acid reductase method, Western blotting and reverse transcription polymerase chain reaction were used to detect NO contents, iNOS protein synthesis and iNOS mRNA expression respectively. Results (1) AVP increased NO contents, iNOS protein synthesis and iNOS mRNA expressions in a concentration dependent manner. Moreover, NO contents [(69 05±5 56) μmol/L and (62 86±6 05) μmol/L], iNOS protein synthesis (0 73±0 06 and 0 64±0 05) and iNOS mRNA expressions (0 70±0 03 and 0 66±0 06) of 10 -7 mol/L AVP group and 10 -6 mol/L AVP group were both higher than those of control group (29 34±5 34 μmol/L, 0 20±0 05, 0 25±0 04), 10 -9 mol/L AVP group [(31 79±6 59) μmol/L, 0 24±0 07, 0 30±0 06] and 10 -8 mol/L AVP group [(36 87±7 89) μmol/L, 0 30±0 09, 0 31±0 03]. But NO contents, iNOS protein synthesis and iNOS mRNA expressions of 10 -6 mol/L AVP group were both lower than those of 10 -7 mol/L group. (2) 10 -7 mol/L AVP increased NO contents, iNOS protein synthesis and iNOS mRNA expressions in a time dependent manner. Moreover, NO contents [(65 05±5 56) μmol/L and (62 43±6 21)μmol/L], iNOS protein synthesis (0 69±0 07 and 0 65±0 05) and iNOS mRNA expressions (0 69±0 10 and 0 68±0 05) of 36h group and 24 h group were both higher than those of 6 h group [(33 92±4 05) μmol/L, 0 26±0 05, 0 18±0 05] and 12 h group [(45 11±4 33) μmol/L, 0 34±0 04, 0 24±0 05] But NO contents, iNOS protein synthesis and iNOS mRNA expressions of 36 h group were both lower than those of 24h group Conclusion AVP stimulates iNOS NO system activity in cultured cardiac fibroblasts, the enhancement of NO contents may be able to inhibit ventricular remodeling induced by AVP.