The renal anatomy of three species of sparrows, two from mesic areas, the House Sparrow (Passer domesticus) and Song Sparrow (Melospiza melodia), and one salt marsh species, the Savannah Sparrow (Passerculus sandwichensis) was examined. Electron microscopy was used to describe the ultrastructure of the nephron. In addition, stereology was used to quantify the volumes of cortex, medulla, and maj...

The kidney of vertebrates plays a key role in excretion of endogenous waste products and xenobiotics. Active secretion in the proximal nephron is at the basis of this excretion, mediated by carrier proteins including multidrug resistance protein 2 (Mrp2). We previously showed that Mrp2 function is reduced by endothelin-1 (ET-1) through a basolateral B-type receptor, nitric oxide (NO), cGMP, and...

During development of the urogenital tract, fibroblast growth factor 8 (Fgf8) is expressed in mesonephric tubules, but its role in this tissue remains undefined. An evaluation of previously generated T-Cre-mediated Fgf8-deficient mice (T-Cre; Fgf8(flox/Δ2,3) mice), which lack Fgf8 expression in the mesoderm, revealed that the cranial region of the Wolffian duct degenerated prematurely and the c...

Our previous study has shown that the decorated tubules (collectively known as the decorated spongiome) of the contractile vacuole complex (CVC) in Paramecium are the site of fluid segregation, as the binding of microinjected monoclonal antibody (mAb) DS-1 to the tubules reduced the CVC's fluid output. In this study, we showed by immunogold labeling on cryosections that the antigenic sites for ...

The heterodimeric transcription factors, hypoxia-inducible factor (HIF)-1 and HIF-2, are essential for the maintenance of cellular oxygen homeostasis. In response to hypoxia, stabilized HIF-1alpha and HIF-2alpha proteins bind HIF-1beta and initiate expression of genes that alleviate hypoxic stress, including those promoting neovascularization. Both HIF-1 and HIF-2 stimulate transcription of vas...

The Wolffian ducts (proand mesonephric ducts) are the most important and earliest structures formed during the development of the urogenital system in vertebrates including humans. The Wolffian ducts originate in the prospective cervical region of the young embryo but later migrate caudally inducing the development of the pronephric and mesonephric tubules along their migratory route. In additi...

Atrial natriuretic factor (ANF) (1 microM) markedly increased cyclic guanosine monophosphate (cGMP) content in microdissected glomeruli (35-fold) and in microdissected inner medullary collecting ducts (IMCD) (20-fold). ANF caused little or no increase in cGMP content in other nephron segments. The threshold concentration for increased cGMP accumulation by ANF was 0.1-1 nM in IMCD, which is in t...

GRANTHAM, JARED J., AND MAURICE B. BURG. Effect ofuasopressin and cyclic AMP on permeability of isolated collecting tubules. Am. J. Physiol. 21 I (I) : 255-259. rg66.-The effect of vasopressin and cyclic 3’,5’-AMP on the permeability to water and urea of the isolated perfused rabbit collecting tubule was measured. When added to the solution bathing the outside of the tubule, these agents regula...

AVP (1 ,tM) stimulated adenylate cyclase activity in the terminal nephron segments only, i.e., the late portion of the distal convoluted tubule, the cortical and medullary portions ofthe collecting tubule (activity ratios 81, 51, and 97, respectively). As measured in one experiment, nearly one-halfmaximal responses were obtained with 0.1 IU/ml PTH or 0.3 ng/ml SCT in thick ascending limbs and w...