Back to Search
Start Over
Salt-dependent inhibition of epithelial Na+ channel-mediated sodium reabsorption in the aldosterone-sensitive distal nephron by bradykinin.
- Source :
-
Hypertension (Dallas, Tex. : 1979) [Hypertension] 2012 Nov; Vol. 60 (5), pp. 1234-41. Date of Electronic Publication: 2012 Oct 01. - Publication Year :
- 2012
-
Abstract
- We have documented recently that bradykinin (BK) directly inhibits activity of the epithelial Na(+) channel (ENaC) via the bradykinin B2 receptor (B2R)-G(q/11)-phospholipase C pathway. In this study, we took advantage of mice genetically engineered to lack bradykinin receptors (B1R, B2R(-/-)) to probe a physiological role of BK cascade in regulation of ENaC in native tissue, aldosterone-sensitive distal nephron. Under normal sodium intake (0.32% Na(+)), ENaC open probability (P(o)) was modestly elevated in B1R, B2R(-/-) mice compared with wild-type mice. This difference is augmented during elevated Na(+) intake (2.00% Na(+)) and negated during Na(+) restriction (<0.01% Na(+)). Saturation of systemic mineralocorticoid status with deoxycorticosterone acetate similarly increased ENaC activity in both mouse strains, suggesting that the effect of BK on ENaC is independent of aldosterone. It is accepted that angiotensin-converting enzyme represents the major pathway of BK degradation. Systemic inhibition of angiotensin-converting enzyme with captopril (30 mg/kg of body weight for 7 days) significantly decreases ENaC activity and P(o) in wild-type mice, but this effect is diminished in B1R, B2R(-/-) mice. At the cellular level, acute captopril (100 μmol/L) treatment sensitized BK signaling cascade and greatly potentiated the inhibitory effect of 100 nmol/L of BK on ENaC. We concluded that BK cascade has its own specific role in blunting ENaC activity, particularly under conditions of elevated sodium intake. Augmentation of BK signaling in the aldosterone-sensitive distal nephron inhibits ENaC-mediated Na(+) reabsorption, contributing to the natriuretic and antihypertensive effects of angiotensin-converting enzyme inhibition.
- Subjects :
- Aldosterone metabolism
Angiotensin-Converting Enzyme Inhibitors pharmacology
Animals
Calcium metabolism
Captopril pharmacology
In Vitro Techniques
Male
Membrane Potentials drug effects
Mice
Mice, Inbred C57BL
Mice, Knockout
Nephrons cytology
Nephrons metabolism
Patch-Clamp Techniques
Peptidyl-Dipeptidase A metabolism
Receptor, Bradykinin B1 deficiency
Receptor, Bradykinin B1 genetics
Receptor, Bradykinin B2 deficiency
Receptor, Bradykinin B2 genetics
Sodium administration & dosage
Sodium Chloride metabolism
Time Factors
Bradykinin pharmacology
Epithelial Sodium Channels metabolism
Nephrons drug effects
Sodium metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1524-4563
- Volume :
- 60
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Hypertension (Dallas, Tex. : 1979)
- Publication Type :
- Academic Journal
- Accession number :
- 23033373
- Full Text :
- https://doi.org/10.1161/HYPERTENSIONAHA.112.200469