Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P41181 (collecting duct)
 5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent studies suggest that carbon monoxide (CO), which is formed by the enzyme heme oxygenase (HO) during the conversion of heme to biliverdin, shares some of the chemical and biological properties of nitric oxide (NO) and may play roles similar to those of NO. Heme oxygenase activity in the kidney has been reported for many years, and there are some reports on the expression of mRNA for two HO isozymes (HO-1 and HO-2) and cellular localization of HO-1 protein. However, cellular localization of HO-2 protein in the kidney under normal conditions has not been reported. In the present study we examined the expression and distribution of HO-2 mRNA and HO-2 protein in rat kidney using RNA protection assay and light and electron immunocytochemistry. RNA protection assay confirmed constitutive expression of HO-2 transcript in rat kidney. HO-2 immunoreactivity was selectively found in epithelial cells of the thick ascending limb and distal convoluted tubule, connecting tubule cells, and principal cells of the collecting duct. These results suggest that HO-2 is synthesized in the kidney and that HO-2 in the epithelial cells of renal tubules may serve as a source for CO generation under normal conditions.
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PMID:Expression and distribution of heme oxygenase-2 mRNA and protein in rat kidney. 944 32

We used the patch-clamp technique to examine the role of carbon monoxide (CO) in regulating Ca(2+)-activated big-conductance K (BK) channels in the principal cell of the cortical collecting duct (CCD). Application of CORM3 or CORM2, a CO donor, activated BK channels in the CCD, whereas adding inactivated CORM2/3 had no effect. Superfusion of the CCD with CO-bubbled bath solution also activated the BK channels in the cell-attached patches. The effect of CO on BK channels was not dependent on nitric oxide synthase (NOS) because the effect of CORM3 was also observed in the CCD treated with l-NAME, an agent that inhibits the NOS. Adding a membrane-permeable cGMP analog, 8-bromo-cGMP, significantly increased the BK channel in the CCD. However, inhibition of soluble guanylate cyclase failed to abolish the stimulatory effect of CORM3 on BK channels. Moreover, inhibition of cGMP-dependent protein kinase G did not block the stimulatory effect of CORM3 on the BK channels, suggesting that the stimulatory effect of CO on the BK channels was, at least partially, induced by a cGMP-independent mechanism. Western blot demonstrated that heme oxygenase type 1 (HO-1) and HO-2 were expressed in the kidney. Moreover, a high-K (HK) intake increased the expression of HO-1 but not HO-2 in the kidney. A HK intake also increased renal HO activity defined by NADPH-dependent CO generation following addition of heme in the cell lysate from renal cortex and outer medulla. The role of HO in regulating BK channel activity in the CCD was also suggested by experiments in which application of hemin increased the BK channels. The stimulatory effect of hemin on the BK channels was blocked by SnMP, a HO inhibitor. But, adding CORM3 was still able to activate the BK channels in the presence of SnMP. We conclude that CO activates the BK channels, at least partially, through a NO-cGMP-independent pathway and that HO plays a role in mediating the effect of HK intake on the BK channels in the CCD.
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PMID:Carbon monoxide stimulates Ca2+ -dependent big-conductance K channels in the cortical collecting duct. 2323 81