Webb R C, Bohr D F
Blood Vessels. 1979;16(2):71-9.
Helical strips of tail artery from spontaneously hypertensive (SHR) and Kyoto Wistar normotensive rats (WKY) were observed to relax in response to potassium after contraction induced by norepinephrine in potassium-free solution. Helical strips from SHR consistently showed greater relaxation in response to the addition of potassium than did those from WKY. The amplitude of potassium-induced relaxation is believed to be an index of the activity of electrogenic sodium-potassium transport and hence of sodium-potassium ATPase. Thus, the sodium-potassium ATPase activity of SHR vascular smooth muscle is increased as compared to WKY. This interpretation is supported by the observation that ouabain eliminated potassium-induced relaxation in both SHR and WKY strips. Potassium-induced relaxation in SHR was more sensitive to ouabain inhibition than in WKY. Relaxation induced by potassium in SHR and WKY strips was also shown to vary with: (1) the length of incubation in potassium-free solution, and (2) the concentration of potassium added back. The results of these experiments on potassium-induced relaxation serve as evidence that SHR have either an increased intrinsic sodium-potassium ATPase activity, or an enzyme activity that has been stimulated to a greater degree by an elevated intracellular sodium concentration which resulted from the incubation in potassium-free solution.
在无钾溶液中，去甲肾上腺素诱导收缩后，观察到来自自发性高血压大鼠（SHR）和京都Wistar正常血压大鼠（WKY）的尾动脉螺旋条对钾有舒张反应。与WKY的螺旋条相比，SHR的螺旋条对添加钾的舒张反应始终更大。钾诱导的舒张幅度被认为是电生钠钾转运活性的指标，因此也是钠钾ATP酶活性的指标。因此，与WKY相比，SHR血管平滑肌的钠钾ATP酶活性增加。哇巴因消除了SHR和WKY螺旋条中钾诱导的舒张，这一观察结果支持了这一解释。SHR中钾诱导的舒张比WKY对哇巴因抑制更敏感。还表明，SHR和WKY螺旋条中钾诱导的舒张随以下因素而变化：（1）在无钾溶液中的孵育时间，以及（2）重新添加的钾浓度。这些关于钾诱导舒张的实验结果证明，SHR要么具有增加的内在钠钾ATP酶活性，要么具有一种酶活性，该酶活性因在无钾溶液中孵育导致细胞内钠浓度升高而受到更大程度的刺激。
