Craig P Smith

Learn More
We have demonstrated that the kidney plays an important role in iron balance and that metabolically significant reabsorption of this ion occurs in the loop of Henle and the collecting ducts [Wareing M, Ferguson CJ, Green R, Riccardi D, and Smith CP. J Physiol (Lond) 524: 581-586, 2000]. To test the possibility that the divalent metal transporter DMT1(More)
The Lake Magadi tilapia (Alcolapia grahami) is an unusual fish, excreting all its nitrogenous waste as urea because of its highly alkaline and buffered aquatic habitat. Here, using both physiological and molecular studies, we describe the mechanism of branchial urea excretion in this species. In vivo, repeated short-interval sampling revealed that urea(More)
Urea movement across plasma membranes is modulated by specialized transporter proteins that are products of two genes, termed UT-A and UT-B. These proteins play key roles in the urinary concentrating mechanism and fluid homeostasis. We have isolated and characterized a 1.4-kb cDNA from testes encoding a new isoform (UT-A5) belonging to the UT-A transporter(More)
Specialized transporter proteins that are the products of two closely related genes, UT-A (Slc14a2) and UT-B (Slc14a1), modulate the movement of urea across cell membranes. The purpose of this study was to characterize the mouse variants of two major products of the UT-A gene, UT-A1 and UT-A2. Screening a mouse kidney inner medulla cDNA library yielded(More)
The UT-A (SLC14a2) and UT-B (SLC14a1) genes encode a family of specialized urea transporter proteins that regulate urea movement across plasma membranes. In this report, we describe the structure of the bovine UT-B (bUT-B) gene and characterize UT-B expression in bovine rumen. Northern analysis using a full-length bUT-B probe detected a 3.7-kb UT-B signal(More)
The movement of urea across plasma membranes is modulated by facilitated urea transporter proteins. These proteins are the products of two closely related genes, termed UT-A (Slc14a2) and UT-B (Slc14a1). By genomic library screening and P1 artificial chromosome "shotgun" sequencing, we have determined the structure of the mouse UT-A gene. The gene is >300(More)
To investigate the role of inner medullary collecting duct (IMCD) urea transporters in the renal concentrating mechanism, we deleted 3 kb of the UT-A urea transporter gene containing a single 140-bp exon (exon 10). Deletion of this segment selectively disrupted expression of the two known IMCD isoforms of UT-A, namely UT-A1 and UT-A3, producing UT-A1/3(-/-)(More)
The blood-seminiferous tubule barrier is responsible for maintaining the unique microenvironment conducive to spermatogenesis. A key feature of the blood-testis barrier is selective permeability to solutes and water transport, conferred by the Sertoli cells of the seminiferous tubules (SMTs). Movement of fluid into the lumen of the seminiferous tubule is(More)
1. In vivo microinjections of 55FeCl3 were made to assess renal iron (Fe2+/3+) transport in the anaesthetized rat. 2. Following microinjection into proximal convoluted tubules (PCTs), 18.5 +/- 2.9 % (mean +/- s.e.m., n = 11) of the 55Fe was recovered in the urine. This recovery was not dependent on the injection site indicating that iron is not reabsorbed(More)
Marine elasmobranch fishes retain relatively high levels of urea to balance the osmotic stress of living in seawater. To maintain osmotic balance and reduce the energetic costs of making urea, it is important for these animals to minimize urea excretion to the environment. We have isolated a novel 2.2-kb cDNA from Squalus acanthias (spiny dogfish shark)(More)