Milesi Verónica, Raingo Jesica, Rebolledo Alejandro, Grassi de Gende Angela O
Anatomía y Fisiología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
J Soc Gynecol Investig. 2003 Sep;10(6):339-46. doi: 10.1016/s1071-5576(03)00117-5.
To identify K+ channels of smooth muscle of human umbilical artery using the patch-clamp technique and to study their effect on resting tone of umbilical artery rings.
Whole-cell and single-channel patch-clamp recordings in enzymatically isolated smooth muscle cells were made. Measurements of developed isometric force were performed on intact tissue.
Delayed rectifier K+ channels (KDR) and large-conductance Ca2+-activated K+ channels (BKCa) contribute to the whole-cell voltage- and time-dependent outward K+ current, as it was specifically inhibited by 5 mM 4-aminopyridine (4-AP; KDR blocker) (92 +/- 4% at 0 mV, n = 7), by 1 mM tetraethylammonium (TEA; BKCa blocker) (71 +/- 4% at +60 mV, n = 4), and by 200 nM iberiotoxin (BKCa blocker) (64 +/- 7% at +60 mV, n = 4). In outside-out patches, BKCa channels had a single-channel conductance of 132 +/- 4 pS (n = 24) in asymmetric K+ conditions and 216 +/- 4 pS (n = 4) in a symmetric K+ gradient. The activity of the BKCa channels was significantly augmented by 1 microM Ca2+ in the inside-out configuration. 4-AP had no effect on resting tone of intact arterial rings. TEA produced contraction of arterial rings whereas phloretin, an activator of BKCa, relaxed them, which means that BKCa channels are functional in intact tissue and are involved in the maintenance of resting tone in this human vessel.
The identities of K+ channels in the human umbilical artery were shown using the patch-clamp technique, and the physiologic effect of K+ channels on resting tone was documented.
采用膜片钳技术鉴定人脐动脉平滑肌的钾通道，并研究其对脐动脉环静息张力的影响。
对酶分离的平滑肌细胞进行全细胞和单通道膜片钳记录。对完整组织进行等长收缩力测量。
延迟整流钾通道（KDR）和大电导钙激活钾通道（BKCa）参与了全细胞电压和时间依赖性外向钾电流，因为5 mM 4-氨基吡啶（4-AP；KDR阻滞剂）可特异性抑制该电流（在0 mV时为92±4%，n = 7），1 mM四乙铵（TEA；BKCa阻滞剂）可抑制该电流（在+60 mV时为71±4%，n = 4），200 nMiberiotoxin（BKCa阻滞剂）可抑制该电流（在+60 mV时为64±7%，n = 4）。在向外膜片模式下，BKCa通道在不对称钾条件下的单通道电导为132±4 pS（n = 24），在对称钾梯度下为216±4 pS（n = 4）。在向外膜片模式下，1 μM Ca2+可显著增强BKCa通道的活性。4-AP对完整动脉环的静息张力无影响。TEA可使动脉环收缩，而BKCa激活剂根皮素可使动脉环舒张，这意味着BKCa通道在完整组织中具有功能，并参与维持该人体血管的静息张力。
采用膜片钳技术揭示了人脐动脉钾通道的特性，并记录了钾通道对静息张力的生理影响。
