Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By in vitro experiments on rabbit bladder, we reassessed the traditional view that mammalian urinary bladder lacks ion transport mechanisms. Since the ratio of actual-to-nominal membrane area in folded epithelia is variable and hard to estimate, we normalized membrane properties to apical membrane capacitance rather than to nominal area (probably 1 muF approximately 1 cm2 actual area). A new mounting technique that virtually eliminates edge damage yielded resistances up to 78,000 omega muF for rabbit bladder, and resistances for amphibian skin and bladder much higher than those usually reported. This technique made it possible to observe a transport-related conductance pathway, and a close correlation between transepithelial conductance (G) and short-circuit current (Isc) in these tight epithelia. G and Isc were increased by mucosal (Na+) [Isc approximately 0 when (Na+) approximately 0], aldosterone, serosal (HCO-3) and high mucosal (H+); were decreased by amiloride, mucosal (Ca++), ouabain, metabolic inhibitors and serosal (H+); and were unaffected by (Cl-) and little affected by antidiuretic hormone (ADH). Physiological variation in the rabbits' dietary Na+ intake caused variations in bladder G and Isc similar to those caused by the expected in vivo changes in aldosterone levels. The relation between G and Isc was the same whether defined by diet changes, natural variation among individual rabbits, or most of the above agents. A method was developed for separately resolving conductances of junctions, basolateral cell membrane, and apical cell membrane from this G--Isc relation. Net Na+ flux equalled Isc. Net Cl- flux was zero on short circuit and equalled only 25% of net Na+ flux in open circuit. Bladder membrane fragments contained a Na+-K+-activated, ouabain-inhibited ATPase. The physiological significance of Na+ absorption against steep gradients in rabbit bladder may be to maintain kidney-generated ion gradients during bladder storage of urine, especially when the animal is Na+-depleted.
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PMID:Na+ transport by rabbit urinary bladder, a tight epithelium. 0 12

The contractile vacuole complex serves to excrete excess cytosolic water from protists. In the amoeba, Dictyostelium discoideum, the organelle had a bipartite morphology: a large main vacuole (bladder) marked by lumenal alkaline phosphatase was surrounded by numerous satellite vacuoles (spongiomes). Bladders and spongiomes have now been purified for the first time. The spongiome membranes had a high density of surface projections identified as catalytically-active vacuolar proton pumps (V-H(+)-ATPase). Spongiomes were resolved from the pump-poor bladders by immunogold buoyant density shift with antibodies to the V-H(+)-ATPase; they contained little protein other than this pump. It appears that, following homogenization, most of the spongiome dissociated from bladders and populated the proton pump-rich membrane fraction called acidosomes. Isolated bladders were enriched > 40-fold in alkaline phosphatase and phosphodiesterase, the activities of which were > 85% latent. Bladders depleted of spongiomes bore several distinctive polypeptides; they also had an excess of the basepieces of the proton pump over the catalytic heads. Bladder membranes were also lipid-rich and had a distinctive lipid composition. We conclude that the contractile vacuole system in Dictyostelium is a complex of discrete, separable bladder and spongiome membranes. The V-H(+)-ATPase in the spongiome may catalyze the primary energy transduction step for pumping water out of the cytoplasm.
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PMID:Isolation and initial characterization of the bipartite contractile vacuole complex from Dictyostelium discoideum. 829 79

Bladder filling depends upon the coordinated control of a storage chamber, the bladder body, and its outlet, the bladder base and urethra. Bladder emptying results from development of force in the bladder body and relaxation of the outlet. Muscle strips from bladder body reveal phasic characteristics, whereas the strips from urethral wall are tonic. To determine whether the compositions of myosin heavy chain (MHC) isoforms and the level of myosin light chain (MLC) phosphorylation contribute to the regional variation in the contractile states of the bladder smooth muscle, we analyzed the levels of MLC phosphorylation and the expression of myosin isoforms in smooth muscle tissues from different regions of the urinary bladder. Strips of bladder from the dome, mid body, base of the bladder and urethra were removed and analyzed for the levels of MLC phosphorylation at the resting tone. The expression of MHC isoforms that differ in the C-terminus (SM1 and SM2) and in the N-terminal region (SM-A and SM-B), formed by alternative splicing of the pre-mRNA at either the 3' end or the 5' end, respectively, was analyzed. The expression of these isoforms was characterized at the mRNA and protein levels using reverse transcriptase-polymerase chain reaction (RT-PCR), SDS-PAGE, and Western blotting. The levels of MLC phosphorylation were 35.5 +/- 4.6, 24.7 +/- 2.2, 13.6 +/- 2.1, and 12.8 +/- 2.7 for dome, mid bladder body, base and urethra respectively. Almost 100% of the MHC mRNA in the dome, mid bladder body, and base contains a 7-amino acid insert near the ATP-binding region, whereas the MHC in the urethral smooth muscle is only 81% inserted. Prior studies have shown that inserted myosin has a two-fold higher actin-activated ATPase activity compared to the myosin isoform that lacks the insert, and the maximum velocity of shortening of smooth muscle containing this insert is high compared to muscle that do not contain the insert. The expression of SM1 and SM2 were not significantly different. Our data suggests the presence of a high degree of inserted myosin and LC20 phosphorylation in the bladder dome and mid-body helps to facilitate rapid force development and emptying. Non-inserted myosin and the low level of MLC phosphorylation in the urethra may contribute to slowly or non-cycling myosin cross bridges and the maintenance of a tonic or contracted state during bladder filling.
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PMID:Myosin light chain phosphorylation at resting level and the composition of myosin isoforms in the bladder body and urethra. 1057 76

There is a clear relationship between the pelvic floor muscles and urinary systems, which relates to urgency, frequency, incontinence, pelvic pain, and bowel complaints. The specific mechanisms which relate these two systems are not clear. Improved understanding of the relation between the pelvic floor muscles and bladder function is clinically relevant in establishing effective treatments to such problems as incontinence, secondary to birth. The following tissues were collected from normal adult female rabbits: pubococcygeus (Pc) and ischiocavernosus/bulbospongiosus (Ic/Bs) pelvic floor muscles. Bladder body muscle and mucosa, bladder base muscle and mucosa, and leg skeletal muscle were also collected. The following enzymatic assays were performed on each tissue: citrate synthase (CS), sarcoplasmic-endoplasmic reticular ATPase (SERCA), and choline acetyltransferase (ChAT). CS and SERCA activities were significantly higher in the Pc compared with the Ic/Bs pelvic floor muscles, whereas the ChAT activity of the Ic/Bs was higher than that of the Pc muscle. Based on our results, the Pc muscle is expected to have a significantly greater capacity to contract and a higher metabolic activity than those of the Ic/Bs muscles. We believe that an understanding of the biochemical activities of these three biomarker enzymes in normal pelvic floor muscles is essential in evaluating the effects of specific experimental dysfunctions created in pelvic floor muscle activity.
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PMID:Citrate synthase, sarcoplasmic reticular calcium ATPase, and choline acetyltransferase activities of specific pelvic floor muscles of the rabbit. 2291 11

A functional impairment of the bladder and heart in a decompensated state caused by a pressure overload is accompanied by a decrease in the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2). The beneficial effects of SERCA2 overexpression in preserving cardiac functions have been previously reported. The aim of the present study was to investigate the effects of overexpressed SERCA2 on bladder functions under physiological and pathological conditions using partial bladder outlet obstruction (BOO) in SERCA2a transgenic Wistar rats (TG). Bladder cystometry and western blot analysis were performed using the wild-type Wistar rats (WT), TG, and BOO models (WTBOO and TGBOO). Persistent overexpression of SERCA2 induces reduced bladder compliance without hypertrophy in TG. BOO induces reduced bladder compliance and hypertrophy in WT and TG in the sub-acute phase, but persistent overexpression of SERCA2a in TG does not aggravate the bladder compliance and hypertrophy. In conclusion, SERCA2a overexpression affects bladder functions under physiological conditions, but not in BOO-induced sub-acute pathological conditions.
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PMID:Persistent overexpression of SERCA2a affects bladder functions under physiological conditions, but not in bladder outlet obstruction-induced sub-acute pathological conditions. 2403 9

Bladder malignancy in the kidney transplant recipient is rare and compared with the general population tends to be of high grade and have an aggressive clinical course. In this report, we describe a case of urothelial carcinoma developing in a kidney transplant recipient 6 years after the diagnosis of polyomavirus nephropathy (PVN). BK virus (BKV) DNA was identified in urine and serum by PCR. The diffuse strong staining of SV40 T-antigen and p53 within both the in situ and invasive carcinoma suggest that BKV may play a role in the oncogenic pathway in this clinical setting.
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PMID:High-grade urothelial carcinoma in a kidney transplant recipient with BK virus infection. 2598 2