Table 1

Effect of ionic strength on inhibition of IK and SK potassium channels

	IK1		SK1		SK2		SK3
	Normal Ionic Strength	Low Ionic Strength	Normal Ionic Strength	Low Ionic Strength	Normal Ionic Strength	Low Ionic Strength	Normal Ionic Strength	Low Ionic Strength
	nM
Apamin	>100	>100	1.3 ± 0.1	0.24^1-a	0.07 ± 0.02	0.09^1-a	0.8 ± 0.1	0.8 ± 0.1
Maurotoxin	1.4 ± 0.4	0.014 ± 0.004	>1000	250 ± 200	>1000	135 ± 65	>1000	45 ± 18
Charybdotoxin	5.9 ± 0.2	0.11 ± 0.03	>1000	N.D.	>1000	N.D.	>1000	370 ± 140

Inhibition of ionomycin-stimulated ⁸⁶Rb efflux IC₅₀. Normal ionic strength, 135 mM NaCl, 5.4 mM KCl, 2 mM mM CaCl₂, 0.8 mM MgCl₂, 10 mM HEPES, 5 mM glucose, and 0.1% BSA. Low ionic strength, 18 mM NaCl, 1 mM CaCl2, 3 mM KCl, 10 mM Tris-HCl, 250 mM sucrose, and 0.1% BSA. Values are averages of two to six separate experiments.

N.D., not determined.
↵1-a Values are averages of duplicate observations in a single experiment.