Biomedical subjects

N Brunskill

Publications and source records attributed to N Brunskill.

2 recordsLinked to original sources

PubMed1991

Changes in lipid environment decrease Na, K-ATPase activity in obstructive nephropathy.

Unilateral ureteral obstruction markedly alters sodium and water reabsorption by the affected kidney. These abnormalities may be due, at least in part, to decreased Na,K-ATPase activity in various segments of the nephron during obstruction. The reason for this decreased activity has, however, remained speculative. The present study examines the potential mechanisms underlying the decreased Na,K-ATPase activity in obstruction. The Na,K-ATPase activity was markedly reduced in basolateral membrane vesicles prepared from the cortex of the obstructed kidney of rats with unilateral ureteric obstruction of 24 hours duration when compared to basolateral membrane vesicles from contralateral kidneys of the same rats or to basolateral membrane vesicles from kidneys of sham operated animals. However, no such difference was present three days post-release of unilateral ureteric obstruction. When basolateral membrane vesicles were incubated with sodium dodecyl sulphate to permeabilize the vesicles, no difference in the proportion of enzyme latency was detected between the basolateral membrane vesicles from obstructed kidneys and those from sham operated rats. Immunoblotting with antibodies to the alpha subunit of Na,K-ATPase revealed equal amounts of enzyme in the basolateral membrane vesicles from contralateral kidneys, obstructed kidneys and sham operated rats. When incubated with liposomes under conditions conducive to fusion and lipid exchange the activity of Na,K-ATPase in basolateral membrane vesicles from obstructed kidneys was reconstituted almost to normal levels. This increase in enzyme activity did not occur in basolateral membranes from contralateral kidneys or in membranes from kidneys of sham operated rats incubated in the same manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗

PubMed1991

Localization and polar distribution of several G-protein subunits along nephron segments.

Guanine nucleotide binding proteins (G-proteins) are heterotrimeric proteins involved in signal transduction in epithelia. In addition to possessing a polarized epithelium the nephron is composed of well defined segments, each with distinct receptors, transporters and other functions. Since different G-proteins interact with different receptors, a differential distribution of the various G-protein subunits would be expected. To investigate this possibility, polyclonal antipeptide antibodies to several G-protein subunits were used to examine the distribution of these proteins in nephron segments and their localization to apical or basal membrane domains. Immunoblotting of cortical membrane vesicles demonstrated the presence of G-proteins in both the brush border and basolateral membrane. Staining with G alpha common and G alpha s antibodies demonstrated more of these G-protein subunits in the brush border than basolateral membrane. G-protein beta subunits were also present in greater quantity in brush border membranes. Immunocytochemical analysis demonstrated good antigenic preservation and basically confirmed the results of immunoblotting of renal cortex. G-proteins were also found to be differentially distributed in the medulla, the amounts increasing with proximity to inner medulla. Only G alpha s and G beta subunits were demonstrated in glomeruli, but all subunits examined were detected in brush borders of proximal and apical membrane of distal tubules in cortex. In outer medulla G alpha s was detected in both basolateral and brush borders of some tubules and only brush borders of others, G alpha i2 and G beta were found in brush border and G alpha i3 was not detected in this area.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗