In order to investigate the effect of TGFβ1 gene transfer on the biological characteristics, the effects of gene transfer and supernatant of transfected osteoblasts on the proliferation and ALP activity of osteoblasts were detected by3H-TdR and MTT. Our results showed that TGFβ1 gene transfer had no effect on the biological characteristics and the activated supernatant of transfected osteoblasts stimulated proliferation and inhibited ALP activity of osteoblasts. TGFβ1 gene transfer could promote the expression of TGFβ1 and the biological characteristics of transfected osteoblasts were stable, which might be helpful for gene therapy of bone defectsin vivo.
The effect of nitric oxide donor sodium nitroprusside (SNP) on resting membrane potential (Em) and potassium currents of the bronchial smooth muscle cells from rats was investigated. All experiments were conducted in conventional whole-cell configuration. The changes of Em and potassium currents after addition of 0.1 mmol/L SNP were measured under the current-clamp mode and the voltage-clamp mode respectively. Results showed that (1) SNP could decrease the Em from −33.8±7.4 mV to −43.7±6.7 mV (n=10,P<0.01); (2) SNP could increase the Ca2+-activated K+ channel peak currents under ramp protocol from 466.9±180. 1 pA to 597.7±237.6 pA (n=7,P<0.01), and the currents under pulse protocol at +50 mV were increased from 544.2±145.4 pA to 678.1±206.2 pA (n=6,P<0.05); (3) SNP also could increase voltage-gated K+ channel peak currents under ramp protocol from 389.6±84.1 pA to 526.7±98.7 pA (n=7,P<0.01), the currents under pulse protocol at +50 mV were increased from 275.7±85.2 pA to 444.3±128.5 pA (n=6,P<0.01). It was concluded that SNP increases the activities of Ca2+-activated K+ channels and voltage-gated K+ channels and leads to K+ efflux and hyperpolarization of the cell membrane, resulting in a decrease of the cell excitement.