Silver, Randi B., and Manoocher Soleimani. H1-K1-ATPases: regulation and role in pathophysiological states. Am. J. Physiol. 276 (Renal Physiol. 45): F799–F811, 1999.—Molecular cloning experiments have identified the existence of two H1-K1-ATPases (HKAs), colonic and gastric. Recent functional and molecular studies indicate the presence of both transporters in the kidney, which are presumed to m...

In ancient Roman mythology, Janus is the god of beginnings and transitions. Janus has two faces, one looking back into the past and one looking ahead into the future (Figure 1). According to Ovid, having two faces also enabled him to never turn his back on his adored Cardea. In the figurative sense, something that is Janus‐headed is ambivalent and must be seen in context. In this regard, potass...

Potassium (K(+)) is an essential nutrient and the most abundant cation in plant cells. Plants have a wide variety of transport systems for K(+) acquisition, catalyzing K(+) uptake across a wide spectrum of external concentrations, and mediating K(+) movement within the plant as well as its efflux into the environment. K(+) transport responds to variations in external K(+) supply, to the presenc...

Tonic inhibitory GABA(A) receptor-mediated currents are observed in numerous cell types in the CNS, including thalamocortical neurons of the ventrobasal thalamus, dentate gyrus granule cells, and cerebellar granule cells. Here we show that in rat brain slices, activation of postsynaptic GABA(B) receptors enhances the magnitude of the tonic GABA(A) current recorded in these cell types via a path...

Glutamate uptake, mediated by electrogenic glutamate transporters largely localized in astrocytes, is responsible for the clearance of glutamate released during excitatory synaptic transmission. Glutamate uptake also determines the availability of glutamate for extrasynaptic glutamate receptors. The efficiency of glutamate uptake is commonly estimated from the amplitude of transporter current r...

Pseudohypoaldosteronism (PHA) types I and II are curious genetic disorders that share hyperkalemia as a predominant finding. Together they have become windows to understanding new molecular physiology in the kidney. Autosomal recessive PHAI results from mutations in the epithelial sodium channel (ENaC), whereas autosomal dominant PHAI is characterized by mutations in the mineralocorticoid recep...

Site-specific electrostatic measurements have been limited to soluble proteins purified for in vitro spectroscopic characterization or proteins of known structure; however, comparable measurements have not been made for functional membrane bound proteins. Here, using an electrochromic fluorophore, we describe a method to monitor localized electric field changes in a voltage-gated potassium chan...