In the renal cortex, immunolight microscopy revealed strong expression of AQP1 in the apical and basolateral membrane
of epithelial cells at the proximal straight / convoluted tubule of ND, respectively (Figs.
Molecular cloning and expression of a member of the aquaporin family with permeability to glycerol and urea in addition to water expressed at the basolateral membrane
of kidney collecting duct cells.
The acinar basolateral membrane
has receptors for secretion of cholecystokinin, acetylcholine and vasoactive intestinal peptide.
Anions are taken up at the basolateral membrane
primarily by organic anion transporter (OAT) 1 and 3 and secreted at the apical membrane by the multidrug resistance proteins (MRP) 2 and 4 (Masereeuw et al., 1999), while cations are mainly taken up by organic cation transporter (OCT) 2 and are eliminated by multidrug and toxin extrusion proteins (MATE) 1 and 2K (Biermann et al., 2006; Cetinkaya et al., 2003; Sauzay et al., 2016) and P-glycoprotein (P-gp).
The work horses for detoxification are 1) MRP1, the transmembrane transporter serving most cells in the body for exporting toxins to circulation, 2) OATP, the basolateral membrane
transporter which moves toxin conjugates from the blood into the hepatocytes or renal tubule epithelial cells, and 3) MRP2, the apical transporter that moves toxin conjugates (and some bile salts) into the bile canaliculus or renal proximal tubule lumen.
The heterodimeric organic solute transporter OST[alpha]-OST[beta] (OST[alpha], gene SLC51A; OST[beta], gene SLC51B) is expressed in the basolateral membrane
of enterocytes and effluxes BS to the portal blood.
Based on the rat model studies mainly, the bile salt independent pathway needs chemical and electrical driving forces generated by the Na-K ATPase in the basolateral membrane
NIS was positive in the basolateral membrane
in up to 10% of the cells of ectopic samples 3, 4, and 5.
Grade 0: no reaction or <10% reactivity in tumour cells; grade 1+: weak reactivity >10% of the tumour cells; with reactivity only in part of the membrane; grade 2+: moderate reactivity in >10% of the cells, with staining across the lateral and basolateral membrane
; grade 3+: strong reactivity with intense staining of the lateral and basolateral membrane
in >10% of the cells.
Most of these solutes are carried via a series of [Na.sup.+]-coupled cotransporters or exchangers, which utilise the transmembrane [Na.sup.+] gradient generated by NKA on the basolateral membrane
In order to secrete chloride across the apical membrane of the epithelial cells, the basolateral membrane
has to establish a driving force for anion efflux via anion channels (e.g., cystic fibrosis transmembrane conductance regulator, CFTR, or [Ca.sup.2+]-sensitive chloride channels) located in the apical membrane (Figure 2).
The general finding of Aqp3 protein in the basolateral membrane
of chloride cells suggests that this aquaporin is participating in cell volume regulation and may take part in nitrogen excretion as well.