Correction to: Effects of enriched-potassium diet on cardiorespiratory outcomes in experimental non-ischemic chronic heart failure

Correction to: Biological Research (2021) 54:43 https://doi.org/10.1186/s40659-021-00365-z

Following publication of the original article [1], the Figs. 2, 3 and 4 are misplaced. The correct order of figures is given in this erratum (Figs. 1, 2, 3, 4, 5, 6).

Fig. 1

Dietary K⁺ supplementation decreases arrhythmia incidence, cardiac sympathetic tone and improves spontaneous baroreflex in CHF rats. A Representative recording of heart rate (HR) tachograms obtained from one Sham rat, one CHF rat and one CHF+K⁺ rat. Arrowheads indicate arrhythmic events. Note that K⁺ supplemented diet reduces arrhythmic events in CHF. B Summary data showing arrhythmia index (events/hour). C Heart rate responses (ΔHR) after sympathetic blockade with propranolol (1 mg/kg). D ΔHR after parasympathetic blockade with atropine (1 mg/kg). E Baroreflex sensitivity (BRS) during spontaneous changes in HR and mean arterial pressure (MAP). Each dashed line represents the tachycardic or bradycardic slope. *P < 0.05 vs Sham, ^#P < 0.05 vs CHF+K⁺. Holm Sidak post hoc after One-Way ANOVA, n = 5 rats per group

Fig. 2

Daily dietary K⁺ supplementation improves breathing in CHF rats. A Representative ventilation recordings of ventilatory flow (ml/s), breath-to-breath interval (B–B_i, s) and tidal volume (V_T, ml) obtained from one Sham rat, one CHF rat and one CHF+K⁺ rat. B Representative Poincare plots showing B–B_i variability. C–D Summary data displaying SD1 and SD2 in all groups. Note that irregularity of B–B_i in CHF is markedly improve by dietary K⁺ supplementation. E Summary data showing changes in breathing irregularity score (%). F Coefficient of variation of V_T amplitudes (%). K⁺ supplemented diet significantly reduces V_T oscillations in CHF. *P < 0.05 vs Sham, ^#P < 0.05 vs CHF+K⁺. Holm Sidak post hoc after One-Way ANOVA, n = 5 rats per group

Fig. 3

Central chemoreflex drive is normalized by K⁺ supplementation in CHF rats. A Representative recording of tidal volume (V_T) and respiratory frequency (Rf) during normoxia (F_iO₂ 21%), hypercapnia (F_iCO₂ 7%) and hypoxia (F_iO₂ 10% in one Sham rat, one CHF rat and one CHF+K⁺ rat. B–C Summary data showing the magnitude (ΔV_E, ml/min/100 g) and gain (ΔV_E/%F_iCO₂) of the ventilatory response to hypercapnia (HCVR). Note that K⁺ supplementation totally restored normal HCVR in CHF rats. D–E Summary data showing the magnitude (ΔV_E, ml/min/100 g) and gain (ΔV_E/%F_iO₂) of the hypoxic ventilatory response (HVR). *P < 0.05 vs Sham, ^#P < 0.05 vs CHF+K⁺. Holm Sidak post hoc after One-Way ANOVA, n = 5 rats per group

Fig. 4

Dietary K⁺ supplementation attenuates cardiorespiratory coupling in CHF. A Representative traces of ventilatory flow (Flow, ml/s) and arterial blood pressure (BP, mmHg) in one Sham rat, one CHF rat and one CHF+K⁺ rat. Tidal volume (V_T) is marked in blue while systolic blood pressure (SBP, mmHg) is shown in red. Note that in CHF rats, oscillations in ventilation are phase with increases in SBP, reflecting a positive interaction between signals. B Summary data showing the magnitude of coherence between V_T and SBP centered at the very low frequency (vLF) peak of V_T. C Summary data showing coherence function between respiratory frequency (R_F) and heart rate (HR). *P < 0.05 vs Sham, ^#P < 0.05 vs CHF+K⁺. Holm Sidak post hoc after One-Way ANOVA, n = 5 rats per group

Fig. 5

Echocardiographic parameters and plasmatic Na⁺ and K⁺ concentration. A Representative echocardiography image of the left ventricle (LV) from one rat per group. LV-end systolic diameter (LVESD, yellow arrow) and LV-end diastolic diameter (LVEDD, red arrow). B LVEDD. C LVESD. D LV-end diastolic volume (LVEDV). E LV-end systolic volume (LVESV) (F) Stroke volume (SV). G Ejection fraction (EF). Note that K⁺ dietary supplementation has no effects on cardiac diameters and volumes in CHF condition. (H) Daily food (g/day/rat) and I water intake (ml/rat/day) in Sham, CHF and CHF+K⁺ groups. J Summary data showing sodium (Na⁺) and K potassium (K⁺) ion concentration (mmol/L) in all groups. Note that Na⁺ concentration decreases in CHF+K⁺ while K⁺ concentration is significantly higher. *p < 0.05 vs Sham, ^#p < 0.05 vs CHF.Holm Sidak post hoc after One-Way ANOVA, n = 5 rats

Fig. 6

Dietary K⁺ supplementation improves cardiac diastolic function in CHF rats. A Representative recording of left ventricle (LV) intraventricular pressure from one Sham rat, one CHF rat and one CHF+K⁺ rat (Upper panel). Lower panel shows ventilatory flows in each section. Note that end diastolic pressure (EDP) is modulated by the ventilatory cycle. B End diastolic pressure volume relationship assessed by single-beat PV-loop analysis during the expiratory and inspiratory phases of the breathing cycle. C Summary data of normalized EDP (nEDP) during inspiration and expiration. Note that the EDP was severely modulated by the ventilatory cycle in CHF rats and this was abolished by K⁺ diet supplementation. D Summary data showing percent changes in Δintraventricular pressures at Exp-Insp. Two-way ANOVA (C) and One-way ANOVA (D), followed by Holm Sidak posthoc. ^‡P < 0.05 vs. Insp; *P < 0.05 vs. Sham, #P < 0.05 vs CHF+K⁺ n = 5 rats per group

The original article has been corrected.