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. 2010 Jan 28;87(1):60–72. doi: 10.1093/cvr/cvq029

Figure 6.

Figure 6

β-Adrenoceptors and autonomic modulation. (A) Representative monophasic action potential recordings at a pacing cycle length of 200 ms in isolated, beating hearts after mechanical AV block. (B) Mean action potential durations during fixfrequent pacing at baseline, during infusion of esmolol 1.7 × 10−6 M, orciprenaline 1.6 × 10−6 M; and orciprenaline 1.6 × 10−6 M plus esmolol 1.7 × 10−6 M. Mean of 19–33 action potentials from 10 to 11 WT hearts and 11 to 31 action potentials from 10 to 12 ΔKPQ-SCN5A hearts. At long cycle lengths, number of action potentials was reduced to five WT, seven ΔKPQ-SCN5A, due to fast intrinsic heart rates. (C) β-Adrenoceptor binding was decreased in ΔKPQ-SCN5A mouse hearts. Specific binding of 125I-ICYP to β-adrenoceptors on cryofixated myocardial short axis sections in n = 4–5 per genotype. Binding is expressed as counts/min/mm2. Inset shows examples of total ICYP and non-specific binding in two representative hearts.