The mechanism underlying the positive inotropic effect of angiotensin II in the isolated perfused rabbit heart: a 31P NMR study.
Related Articles The mechanism underlying the positive inotropic effect of angiotensin II in the isolated perfused rabbit heart: a 31P NMR study.
Int J Biochem Cell Biol. 2003 Jun;35(6):984-91
Authors: Mielke M, Paterson DJ, Sang AE, Radda GK, Clarke K
Activation of the Na(+)/H(+) exchanger may play an important role in the development of cardiac hypertrophy. Isolated ventricular myocyte studies have suggested that angiotensin II (AII) has direct positive inotropic effect caused by intracellular alkalinization due to increased Na(+)/H(+) exchange, but whether this occurs in the whole heart is unknown. Consequently, we have used non-invasive 31P NMR spectroscopy to determine whether AII stimulation alters energetics or intracellular pH (pH(i)) in the intact beating rabbit heart. Heart rate (HR) and developed pressure (DP) were recorded continuously in isolated perfused rabbit hearts, simultaneously with pH(i) and high energy phosphate metabolite levels measured using 31P NMR spectroscopy. AII (11 nM) increased developed pressure by 14+/-2 mmHg (P