Sodium‐potassium pump current in smooth muscle cells from mesenteric resistance arteries of the guinea‐pig

Abstract

The maintenance of electrochemical gradients for extracellular Na¤ and intracellular K¤ ions is essential for almost all cells and is mainly achieved by the action of Na¤,K¤-adenosine triphosphatase (ATPase). The electrogenic nature of the Na¤-K¤ pump has been described: one forward cycle provides the outward current resulting in the expulsion of three Na¤ ions and the uptake of two K¤ ions for each hydrolysed ATP. To assess the function of Na¤,K¤-ATPase, including its electrogenic characteristics, the Na¤-K¤ pump currents have been measured by voltageclamp techniques in several cell types, such as cardiac myocytes (

Bidirectional Interactions between H-Channels and Na+–K+Pumps in Mesencephalic Trigeminal Neurons

“…The temperature coefficient (Q 10 ) of Na ϩ -K ϩ pumps has been reported to be ϳ2 between 20 and 37°C (Glitsch and Pusch, 1984;Thompson and Prince, 1986;Nakamura et al, 1999). This value is similar to those of voltage-gated ion channels (Beam and Donaldson, 1983;Nobile et al, 1990), although the exact value of Q 10 for h-channels is not known yet.…”

Transient Receptor Potential Channel 6–Mediated, Localized Cytosolic [Na + ] Transients Drive Na + /Ca 2+ Exchanger–Mediated Ca 2+ Entry in Purinergically Stimulated Aorta Smooth Muscle Cells

“…In contrast to Ca 2ϩ sparks lasting hundreds of milliseconds, the [Na ϩ ] sub-PM transients last tens of seconds to minutes. Although these slow kinetics may be related to the temperature sensitivity of the Na ϩ /K ϩ -ATPase, 48 our experiments underline the need to better understand the ultrastructural and molecular nature of the barriers creating localized [Na ϩ ] gradients (reviewed elsewhere 43 ).…”

Effects of amiloride, benzamil, and alterations in extracellular Na+ on the rat afferent arteriole and its myogenic response

“…9) would be consistent with such a mechanism, and Na ϩ -K ϩ -ATPase is reported to be sensitive to physiological changes in intracellular [Na ϩ ] (9, 35). The outward current attributed to the operation of the ouabain-sensitive Na ϩ -K ϩ -ATPase, however, is generally quite small [ϳ1 pA/pF, guinea pig mesenteric artery myocyte (28)], and estimates concerning its contribution to the smooth muscle membrane potential vary considerably (e.g., 4,28,32,39). This issue has not been adequately addressed in the afferent arteriole.…”