Oxidative stress and alpha 1-adrenoceptor-mediated stimulation of the Cl-/HCO3- exchanger in immortalized SHR proximal tubular epithelial cells

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Simao, S (Author) Other; Sonia Fraga (Author) FFUP; Jose, PA (Author) Other; soares-da-silva, p (Author) FMUP

Journal

Title: British Journal of Pharmacology

Vol. 153

Pages: 1445-1455

ISSN: 0007-1188

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 11 Citations

Scopus - 16 Citations

Other information

Authenticus ID: P-004-0A2

DOI: 10.1038/bjp.2008.16

Abstract (EN): Background and purpose: This study evaluated the signalling coupled to the alpha 1-adrenoceptor- induced stimulation of the Cl-/ HCO3- exchanger in hypertension. Experimental approach: The Na+- independent HCO3- transport system activity was assayed as the initial rate of pH(i) recovery after an alkaline load (CO2/HCO3 removal) in immortalized renal proximal tubular epithelial cells from spontaneously hypertensive rat (SHR) and their normotensive control ( Wistar Kyoto rat; WKY). Key results: Noradrenaline increased Cl-/HCO3- exchanger activity with EC50 values of 0.6 and 5.3 mu M in SHR and WKY cells, respectively. These effects were abolished by prazosin, but not by yohimbine. Phenylephrine increased Cl-/HCO3- exchanger activity in SHR and WKY cells ( EC50 of 2.6 and 4.9 mu M, respectively). Phenylephrine-mediated increase in Cl-/ HCO3- exchanger activity in WKY and SHR cells was inhibited by protein kinase C ( PKC), MAPK/ERK kinase (MEK) and p38 mitogen-activated protein kinase ( p38 MAPK) inhibitors. The expression of alpha(1A)- and alpha(1B)-adrenoceptors was identical in WKY and SHR cells. SHR cells generated more H2O2 than WKY cells. In SHR cells, the NADPH oxidase inhibitor apocynin reduced their increased ability to generate H2O2 and abolished their hypersensitivity to phenylephrine, but failed to affect basal Cl-/HCO3- exchanger activity. H2O2-dependent stimulation of Cl-/HCO3- exchange activity was significantly higher in SHR than in WKY cells. Conclusions and implications: Differences between WKY and SHR cells on their sensitivity to alpha 1-adrenoceptor stimulation did not correlate with the abundance of alpha(1A)- and alpha(1B)-adrenoceptors and may be related to the increased generation of H2O2, which may amplify the response downstream of alpha 1-adrenoceptor activation.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11