The effect of taurine supplementation on the renin-angiotensin-aldosterone system of dogs with congestive heart failure

Abstract

The role of taurine in the treatment of congestive heart failure (CHF) in dogs without systemic deficiency is unexplored. Taurine might have beneficial cardiac effects aside from deficit replacement. We hypothesized that oral taurine supplementation administered to dogs with naturally-occurring CHF would suppress the renin-angiotensin aldosterone system (RAAS). Oral taurine was administered to 14 dogs with stable CHF. Serum biochemical variables, blood taurine concentrations, and comprehensive analysis of RAAS variables were compared before and 2 weeks after taurine supplementation added to background furosemide and pimobendan therapy for CHF. Whole blood taurine concentrations increased after supplementation (median 408 nMol/mL, range 248-608 before and median 493 nMol/mL, range 396-690 after; P = .006). Aldosterone to angiotensin II ratio (AA2) was significantly decreased after taurine supplementation (median 1.00, range 0.03-7.05 before and median 0.65, range 0.01-3.63 after; P = .009), but no other RAAS components significantly differed between timepoints. A subset of dogs showed marked decreases in RAAS metabolites after supplementation and these dogs were more likely to have been recently hospitalized for CHF treatment than dogs that did not show marked decreases in classical RAAS metabolites. Overall, taurine only lowered AA2 in this group of dogs, however, response heterogeneity was noted, with some dogs showing RAAS suppression.

Figure 1

Renin–angiotensin–aldosterone system (RAAS) Fingerprints™ at visit 1 (V1) and visit 2 (V2). The size of the sphere indicates the median metabolite value (pmol/L) for the group of dogs for each metabolite. Red spheres indicate classical RAAS metabolites that mediate vasoconstriction and sodium retention, green spheres indicate alternative RAAS metabolites that mediate vasodilation and natriuresis, and blue spheres indicate inert metabolites. Ang 1; angiotensin I, Ang II; angiotensin II, Ang III; angiotensin III, Ang IV; angiotensin IV, AT1R; angiotensin receptor type 1, Ang 1–7; angiotensin 1–7, Ang 1–5; angiotensin 1–5, aldo; aldosterone.

Figure 2

Angiotensin I, angiotensin II, and aldosterone values are shown for each dog at each time point with connecting lines to indicate the same dog. Dots and lines colored red indicate dogs that were hospitalized for treatment of congestive heart failure within 1 week of enrollment. Dots and lines colored black indicate dogs that were hospitalized for treatment of congestive heart failure more than 1 week before enrollment. V1; visit 1 (before taurine supplementation), V2; visit 2 (2 weeks after taurine supplementation).