RESUMO
The effects of protein kinase C (PKC) on the tension and the activity of voltage-dependent delayed rectifier potassium channel (K(y)) were examined in normal and passively sensitized human airway smooth muscle (HASM), by measuring tones and whole-cell patch clamp techniques, and the K(v) activities and membrane potential (E (m)) were also detected. The results showed that phorbol 12-myristate 13-acetate (PMA), a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group (P<0.05), and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. K(v) activities of HASM cells were significantly inhibited by PMA, and the E (m) became more positive, as compared with the DMSO (a PMA menstruum)-treated group (P<0.01). This effect could be blocked by Ro31-8220 (P<0.01). It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced K(v) activity. In passively sensitized HASM rings, this effect was more notable.
RESUMO
The effects of protein kinase C (PKC) on the tension and the activity of voltage-dependent delayed rectifier potassium channel (Kv) were examined in normal and passively sensitized human airway smooth muscle (HASM), by measuring tones and whole-cell patch clamp techniques, and the Kv activities and membrane potential (Em) were also detected. The results showed that phorbol 12-myristate 13-acetate (PMA), a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group (P＜0.05), and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. Kv activities of HASM cells were significantly inhibited by PMA, and the Em became more positive, as compared with the DMSO (a PMA menstruum)-treated group (P＜0.01). This effect could be blocked by Ro31-8220 (P＜0.01). It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced Kv activity. In passively sensitized HASM rings, this effect was more notable.
RESUMO
AIM: To investigate the regulatory effects of voltage-dependent delayed rectifier potassium channel (Kv) on the tension of normal and passively sensitized human airway smooth muscle (HASM). METHODS: By using blockers of potassium channels as tools, the tension of HASM and Kv gene mRNA and protein expressions in normal and asthmatics serum sensitized HASM cells were measured with techniques of reverse transcriptase/polymerase chain reaction (RT-PCR) and immunocytochemistry. RESULTS: (1) 4-aminopyridine (4-AP), the blocker of Kv, caused a concentration dependent constriction in normal HASM rings. The negative logarithm of the drug concentration causing 50% of maximal effect (pD_2) in normal group (2.09?0.09) was significantly different from that in the sensitized group (2.44?0.16, P0.05). (2) There were Kv1.2, Kv1.3 and Kv1.5 mRNA expressions in cultured HASM cells, but only Kv1.5 mRNA (P
RESUMO
AIM:To investigate the activity change of voltage-dependent delayed rectifier potassium channel(Kv) on human airway smooth muscle cells(HASMCs) after transfection of Kv1.5 antisense oligonucleotides(AsOND),and to discuss the regulating mechanism of Kv1.5.METHODS: The mRNA and protein expressions of Kv1.5 in liposome-mediated Kv1.5 AsOND transfected HASMCs were measured with techniques of reverse transcriptase-polymerase chain reaction(RT-PCR) and Western blotting.Kv activities in transfected HASMCs were investigated with whole-cell patch clamp.RESULTS: After HASMC were transfected by liposome-mediated Kv1.5 AsOND,the mRNA and protein expressions of Kv1.5 were decreased,and Kv activity was inhibited,which made the cell membrane potential(Em) inclined to depolarization.CONCLUSION: Transfection of Kv1.5 AsOND made the function of Kv in HASMCs decreased.Kv1.5 may play a critical role in the regulation of Kv activity.