GRK2 blockade with βARKct is essential for cardiac β2-adrenergic receptor signaling towards increased contractility

Table 1 In vivo cardiac functional parameters

Parameter	WT-Sham	βARKct-Sham	B1KO-Sham	βARKct/ B1KO-Sham	WT-MI	βARKct-MI	B1KO-MI	βARKct/ B1KO-MI
Infarct size (% LV free wall)	N/A	N/A	N/A	N/A	41±1.2	42±2.2	40±2.6	43±3.0
FS (%)	41.4±1.3	48.3±2.8^	36.7±2.6^	41.3±2.4^#	18.6±2.2	23.7±1.3⁺	11.0±1.4⁺	19.0±2.4*
EF (%)	72.0±1.0	78.0±2.0^	67.0±2.4^	72.0±2.0^#	37.5±3.0	45.3±2.4⁺	23.7±2.5⁺	38.5±4.2*
Basal HR (min–1)	385±12	402±37	402±27	383±23	392±12	408±10	391±8	389±13
Basal LV +dP/dt _max (mm Hg/s)	4692±363	6835±637^	3572±287^	4576±375^#	3512±220	4900±172⁺	2576±155⁺	3549±231*
Basal LV –dP/dt _min (mm Hg/s)	−4568±452	−6714±536^	−3269±296^	−4782±286^#	−3515±246	−4620±203⁺	−2592±233⁺	−3471±194*
Max. Iso-HR (min–1)	557±36	515±40	405±28^	393±14^	509±24	581±17⁺	399±11⁺	413±20⁺
Max. Iso-LV +dP/dt _max (mm Hg/s)	8825±644	13547±476^	3611±286^	9041±528^#	5641±431	9419±601⁺	2639±139⁺	5628±419*
Max. Iso-LV–dP/dt _min (mm Hg/s)	−7210±430	−8837±491^	−3199±279^	−6344±364^#	−5880±303	−6948±277⁺	−2605±251⁺	−5548±382*

Cardiac parameter values of three-month-old wild type (WT, i.e. C57/B6), βARKct, B1KO and βARKct/B1KO mice measured at 4 weeks after MI or sham operation (Sham). LV +dP/dt_max maximal first derivative of LV pressure rise, LV –dP/dt_min minimal first derivative of LV pressure fall, HR heart rate, FS, fractional shortening, EF ejection fraction, LV Left ventricular, N/A Not applicable, Max. Iso dose: 333 ng/kg body weight. ^#, p<0.05, vs. B1KO-Sham; *, p<0.05, vs. B1KO-MI; ^, p<0.05, vs. WT-Sham; ⁺, p<0.05, vs. WT-MI; n=7 mice/group. One-way ANOVA with Bonferroni test was performed among groups. Data are presented as mean ± SEM.

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