Table 1

Contractile parameters of isolated hearts from 4 and 12 month old guanylyl cyclase A receptor (GC-A) +/+ and −/− mice in the working heart preparation.

Genotype and age (months)
+/+, 4−/−, 4+/+, 12−/−, 12
Basal conditions: preload of 5 ml/min cardiac output, afterload of 50 mm Hg aortic pressure. Data are mean (SEM), n = 5 to 8, *p < 0.05 between −/− and +/+ mice (unpaired t test). Systolic and diastolic pressures are defined as the maximal (peak) and minimal left intraventricular pressures.
Heart rate (beats/min)369 (11)390 (21)381 (17)372 (7)
Mean aortic pressure (mm Hg)51 (0.4)52 (1.2)49 (0.7)47 (0.5)
Left ventricular pressure
    Systolic (maximum)94 (2)91 (4)88 (1.2)82 (2.1)*
    Diastolic (minimum)−6.3 (0.5)−4.2 (3.5)−1.3 (1.8)1.5 (0.6)
    End diastolic6.6 (2)8 (2.4)5.3 (0.5)6.4 (0.6)
Coronary flow (ml/min/g)12.5 (1)11.5 (0.5)12.3 (1.4)10.9 (1.1)
Left ventricular minute work (mm Hg × ml/min)255 (3)259 (5)248 (4)245 (6.7)
Time to peak pressure (ms)34 (0.9)35 (0.8)33 (0.5)33 (0.7)
Time of relaxation (ms)41 (0.6)46 (0.9)*38 (1.2)45 (1.4)*
Time to peak pressure (ms/mm Hg)0.414 (0.015)0.483 (0.021)0.402 (0.006)0.443 (0.009)
Time to half relaxation (ms/mm Hg)0.497 (0.013)0.553 (0.018)0.513 (0.007)0.661(0.009)*
Maximum rate of contraction (+dP/dt, mm Hg/s)2575 (44)2476 (124)2477 (47)2258 (72)*
Maximum rate of relaxation (−dP/dt, mm Hg/s)−2565 (92)−2463 (148)−2403 (76)−1913 (98)*