Figure 4. Dependence of CMF amplitude on isoproterenol concentration in the absence and presence of propranolol.

RBCs were incubated with isoproterenol in the absence (•) and presence (○) of 10⁻⁹ M propranolol for 20 min, at 37 °C. Data are given in terms of the maximal CMF in the frequency range 0.3-35 Hz. The amplitudes are given by δI_max/I (%; means ±s.e.m.) Each independent experiment involved measurements of 15-25 RBCs.