The Involvement of Ser1898 of the Human L-Type Calcium Channel in Evoked Secretion

Table 1

The effect of forskolin on the rate and total catecholamine secretion. The rate of secretion was determined in cells infected with GFP, Hu/wt, the wt human α ₁1.2 subunit, and Hu/S1898A, and the mutant α ₁1.2/S1898A subunit.

Group	# Cells	# Spikes	AVG; # Spikes	Frequency		Secretion
				10–40 sec; (Spike/sec)	Fold	10–40 sec; (pC)	Fold
Noninfected	18	502	27 ± 4.8	0.53 ± 0.02; 𝑅^2=0.995		15.4 ± 1.8
GFP	49	1048	21.4 ± 3.0	0.52 ± 0.01; 𝑅^2=0.989		16 ± 2.5
GFP + FSK^a	21	693	33 ± 3.2	0.79 ± 0.03 𝑅^2=0.994	1.5	26 ± 4.4*	1.6
Hu/wt	43	943	22 ± 2.5	0.57 ± 0.02; 𝑅^2=0.989		17 ± 1.9
Hu/wt + FSK	34	1052	30 ± 4.9	0.86 ± 0.03; 𝑅^2=0.982	1.5	28 ± 4.5*	1.6
Hu/S1898A	42	547	13 ± 1.4	0.35 ± 0.01; 𝑅^2=0.995		10 ± 0.9
Hu/S1898A +FSK	40	953	23.8 ± 3.5	0.46 ± 0.01; 𝑅^2=0.985	1.3	16 ± 2.1*	1.6

Cells were stimulated for 10 sec by 60 mM KCl. Amperometric currents were measured during time range of 10–40 sec, which includes the 10 sec K60 stimulation and a 20 sec poststimulus period.
^a1 μM forskolin (FSK);*𝑃<0.05.