Table 2. The Hill fit parameters for... | Rockefeller University Press

Table 2.

The Hill fit parameters for cytoplasmic regulation data shown in Fig. 1

Species	[Ca²⁺]_L pCa	[Ca²⁺]_C pCa	P_max	P_min (×10³)	K_a/K_i	H_a/H_i	n
					µM
Activation by cytoplasmic Ca²⁺
Human	9	-	0.9 ± 0.3	0.14 ± 0.02	4.0 ± 1.0	2.5 ± 0.4	4–6
Sheep	9	-	0.90 ± 0.03	0.15 ± 0.08	2.0 ± 0.3	2.6 ± 1.3	4–5
Rat	9	-	0.60 ± 0.10	0.20 ± 0.05	3.2 ± 0.5	2.8 ± 0.5	4
Inhibition by cytoplasmic Mg²⁺
Human	4	7	0.03 ± 0.02	0^a	15 ± 4	1.2 ± 0.5	4
Sheep	4	7	0.19 ± 0.06	0^a	18 ± 3	1.4 ± 0.3	3–26
Rat	4	7	0.019 ± 0.015	0^a	13 ± 6	1.3 ± 0.7	10
Human	4	4	0.90 ± 0.06	0^a	5,400 ± 800	0.8 ± 0.2	4–10
Sheep	4	4	0.98 ± 0.10	0^a	1,600 ± 300^b	0.7 ± 0.3	4–7
Rat	4	4	0.95 ± 0.03	0^a	5,500 ± 600	1.6 ± 0.7	5

Species	[Ca²⁺]_L pCa	[Ca²⁺]_C pCa	P_max	P_min (×10³)	K_a/K_i	H_a/H_i	n
					µM
Activation by cytoplasmic Ca²⁺
Human	9	-	0.9 ± 0.3	0.14 ± 0.02	4.0 ± 1.0	2.5 ± 0.4	4–6
Sheep	9	-	0.90 ± 0.03	0.15 ± 0.08	2.0 ± 0.3	2.6 ± 1.3	4–5
Rat	9	-	0.60 ± 0.10	0.20 ± 0.05	3.2 ± 0.5	2.8 ± 0.5	4
Inhibition by cytoplasmic Mg²⁺
Human	4	7	0.03 ± 0.02	0^a	15 ± 4	1.2 ± 0.5	4
Sheep	4	7	0.19 ± 0.06	0^a	18 ± 3	1.4 ± 0.3	3–26
Rat	4	7	0.019 ± 0.015	0^a	13 ± 6	1.3 ± 0.7	10
Human	4	4	0.90 ± 0.06	0^a	5,400 ± 800	0.8 ± 0.2	4–10
Sheep	4	4	0.98 ± 0.10	0^a	1,600 ± 300^b	0.7 ± 0.3	4–7
Rat	4	4	0.95 ± 0.03	0^a	5,500 ± 600	1.6 ± 0.7	5

n indicates the number of experiments. The Hill equation for Ca²⁺ activation is

P_{o} = \frac{P_{max} {([{Ca}^{2 +}] / K_{a})}^{H_{a}}}{(1 + {([{Ca}^{2 +}] / K_{a})}^{H_{a}})} + P_{min} .

The Hill equation for Mg²⁺ inhibition is

P_{o} = \frac{P_{max}}{(1 + {([{Mg}^{2 +}] / K_{i})}^{H_{i}})} .

Parameters that were not adjusted during fitting.

Significantly different to human (P < 0.01).