Table 1.

The pharmacology of BK channels

BKSK1–3SK4/IK
BK, large-conductance Ca2+-sensitive K+ channel; SK, small-conductance Ca2+-sensitive K+ channel; IK, intermediate-conductance Ca2+-sensitive K+ channel; SM, smooth muscle; CKII, casein kinase II; 1-EBIO, 1-ethyl-2-benzimidazolinone; DC-EBIO, 5,6-Dichloro-1-ethyl-1,3-dihydro-2H-benzimidazole-2-one; TEA+, tetraethylammonium ions; TRAM-34, 1-[(2-chlorophenyl)dipenylmethyl]-1H-pyrazole.
SubunitsPore-forming α (4)
 Auxiliary β (4)Pore-forming (4)
 Calmodulin (4)Pore-forming (4)
 Calmodulin (4)
GenesOne Slo gene-encoding α-subunit
 Four β genes (β1–4)KCNN1 (SK1)
 KCNN2 (SK2)
 KCNN3 (SK3)KCNN4
ExpressionVascular and nonvascular SM
 Neurons
 Adrenal glandEndothelium
 Neurons
 Nonvascular SM
 EpitheliumEndothelium
 Epithelium
 Vascular SM (proliferative state)
 Lymphocytes
 Erythrocytes
Calcium-sensitive?YesYes (calmodulin)Yes (calmodulin)
Voltage-dependent?YesNoNo
ModulationPKA, PKG (+), PKC (−)CKIIN/A
Activators/StimulatorsNS1619
 NS1608
 EstrogenRiluzole
 1-EBIO/DC-EBIO
 NS309
 ChlorzoxazoneRiluzole
 1-EBIO/DC-EBIO
 NS309
 Chlorzoxazone
BlockersTEA+
 Iberiotoxin
 Charybdotoxin
 EthanolApamin
 UCL 1684
 Bicuculline
 Dequalinium
 TEA+Charybdotoxin
 TRAM-34
 Clotrimazole
 TEA+
RoleRegulation of smooth muscle excitability
 Regulation of vascular tone, blood pressure, erectile and urinary bladder functionRegulation of endothelial Ca2+
 Regulation of vascular tone and blood pressureRegulation of endothelial Ca2+
 Regulation of vascular tone and blood pressure
DiseaseHypertension
 Erectile dysfunction
 Urinary incontinence
 AtaxiaHypertensionHypertension
 Restenosis