Table 1.

Ca²⁺ uptake (nmol Ca²⁺ mg⁻¹ min⁻¹) by SR vesicles prepared from control, diabetic and insulin-treated diabetic rat hearts in the presence of PKA catalytic subunit or PKC

	Control	Diabetic	Insulin-treated diabetic
PKA
Basal Ca2+-uptake rate	26.51±3.81	50.03±5.71**	27.70±1.52††
Increase in Ca2+-uptake rate	47.63±4.27	26.86±6.24*	41.14±0.61†
PKC
Basal Ca2+-uptake rate	25.07±0.45	34.93±0.78**	25.64±1.94††
Increase in Ca2+-uptake rate	10.10±0.93	0.95±2.53**	12.17±2.45†

The concentration of free Ca²⁺ was 0.58 μM. Uptake was measured after incubation with 50 nM PKA catalytic subunit or 9 μg ml⁻¹ PKC (in the presence of 18.7 μg ml⁻¹ phosphatidylserine) under conditions favorable for phosphorylation, followed by the addition of 5 mM oxalic acid to the reaction mixture. Rates of Ca²⁺ uptake were determined by least-squares linear regression analysis of the data from triplicate experiments. Values are given as means±s.e.m. of 3–4 preparations from different animals in each group.

^*P<0.05

^**P<0.01 versus respective control values.

^†P<0.05

^††P<0.01 versus respective diabetic values.