Table 2.

Effects of [Mg²⁺]_i on phosphorylation-dependent modulation of I_Ca (pA pF⁻¹)

[Mg2+]p (mM)
Phosphorylation conditions†	0.2	1.8
Low (PP2A)	9.8 ± 1.3 (12)	6.7 ± 0.4 (16)
Basal	17.0 ± 2.2 (12)	5.6 ± 1.0 (10)
High (forskolin, IBMX, OA)	36.3 ± 2.1 (3)	7.6‡

Values of n given in parentheses.

^†[Ca²⁺]_i set at 100 nm and [Ca²⁺]_o to 2 mm in all experiments. Currents were measured at 0 mV.

^‡This value is extrapolated by reducing the current density (36.3 pA pF⁻¹) measured at 0.2 mm[Mg²⁺]_i during superfusion with 2 mm[Ca²⁺]_o by 79%, the reduction in current density measured upon increasing [Mg²⁺]_i from 0.2 to 1.8 mm with 0.5 mm[Ca²⁺]_o.