OBJECTIVES: This study investigated the role of angiotensin receptor subtype 1 (AT1) and angiotensin receptor subtype 2 (AT2) in the regulation of Na+-H+ exchanger (NHE) and Na+-HCO3 symporter (NBC) in the infarcted myocardium. BACKGROUND: The cardiac renin-angiotensin system is activated after myocardial infarction (MI), and both angiotensin AT1 and AT2 receptors are upregulated in the myocardium. METHODS: Na+-H+ exchanger isoform-1 and NBC-1 gene expression were determined by reverse transcription polymerase chain reaction and Northern blot analysis; protein levels by Western blot analysis; and activity by measurement of H+ transport in left ventricular (LV) free wall, interventricular septum (IS) and right ventricle (RV) after induction of MI. Rats were treated with placebo, the angiotensin-converting enzyme inhibitor ramipril (1 mg/kg/day), the AT1 receptor antagonist valsartan (10 mg/kg/day) or the AT2 receptor antagonist PD 123319 (30 mg/kg/day). Treatment was started seven days before surgery. RESULTS: Na+-H+ exchanger isoform-1 and NBC-1 messenger RNA (mRNA) expression and protein levels were increased twofold in the LV free wall after MI, whereas no changes were observed in the IS and RV. Na+-dependent H+ flux was increased in the LV free wall. Ramipril inhibited mRNA and protein upregulation of both transporters. Valsartan inhibited the upregulation of NHE-1 mRNA and protein but had no effect on NBC-1 mRNA expression and translation. In contrast, PD 123319 abolished the upregulation of NBC-1 mRNA and protein but had no effect on NHE-1 upregulation. Ramipril and valsartan prevented post-MI increase in NHE-1 activity, whereas ramipril and PD 123319 decreased NBC-1 activity. CONCLUSIONS: Angiotensin II via its AT1 and AT2 receptors differentially controls transcriptional and translational regulation as well as the activity of NHE-1 and NBC-1 in the ischemic myocardium and contributes to the control of pH regulation in cardiac tissue.
OBJECTIVES: This study investigated the role of angiotensin receptor subtype 1 (AT1) and angiotensin receptor subtype 2 (AT2) in the regulation of Na+-H+ exchanger (NHE) and Na+-HCO3 symporter (NBC) in the infarcted myocardium. BACKGROUND: The cardiac renin-angiotensin system is activated after myocardial infarction (MI), and both angiotensin AT1 and AT2 receptors are upregulated in the myocardium. METHODS: Na+-H+ exchanger isoform-1 and NBC-1 gene expression were determined by reverse transcription polymerase chain reaction and Northern blot analysis; protein levels by Western blot analysis; and activity by measurement of H+ transport in left ventricular (LV) free wall, interventricular septum (IS) and right ventricle (RV) after induction of MI. Rats were treated with placebo, the angiotensin-converting enzyme inhibitor ramipril (1 mg/kg/day), the AT1 receptor antagonist valsartan (10 mg/kg/day) or the AT2 receptor antagonist PD 123319 (30 mg/kg/day). Treatment was started seven days before surgery. RESULTS: Na+-H+ exchanger isoform-1 and NBC-1 messenger RNA (mRNA) expression and protein levels were increased twofold in the LV free wall after MI, whereas no changes were observed in the IS and RV. Na+-dependent H+ flux was increased in the LV free wall. Ramipril inhibited mRNA and protein upregulation of both transporters. Valsartan inhibited the upregulation of NHE-1 mRNA and protein but had no effect on NBC-1 mRNA expression and translation. In contrast, PD 123319 abolished the upregulation of NBC-1 mRNA and protein but had no effect on NHE-1 upregulation. Ramipril and valsartan prevented post-MI increase in NHE-1 activity, whereas ramipril and PD 123319 decreased NBC-1 activity. CONCLUSIONS:Angiotensin II via its AT1 and AT2 receptors differentially controls transcriptional and translational regulation as well as the activity of NHE-1 and NBC-1 in the ischemic myocardium and contributes to the control of pH regulation in cardiac tissue.
Authors: Verónica C De Giusti; Alejandro Orlowski; María C Villa-Abrille; Gladys E Chiappe de Cingolani; Joseph R Casey; Bernardo V Alvarez; Ernesto A Aiello Journal: Br J Pharmacol Date: 2011-12 Impact factor: 8.739
Authors: U Muscha Steckelings; Robert E Widdop; Edward D Sturrock; Lizelle Lubbe; Tahir Hussain; Elena Kaschina; Thomas Unger; Anders Hallberg; Robert M Carey; Colin Sumners Journal: Pharmacol Rev Date: 2022-10 Impact factor: 18.923