These experiments were conducted to determine the membrane K+ currents and channels in @entity1 urinary bladder (HTB-9) @entity189 cells in vitro. K+ currents and channel activity were assessed by the whole-cell voltage clamp and by either inside-out or outside-out patch clamp recordings. Cell depolarization resulted in activation of a @entity141 -dependent outward K+ current, 0.57 +/- 0.13 nS/pF at -70 mV holding potential and 3.10 +/- 0.15 nS/pF at 30 mV holding potential. Corresponding patch clamp measurements demonstrated a @entity141 -activated, voltage-dependent K+ channel (KCa) of 214 +/- 3.0 pS. Scorpion venom peptides, charybdotoxin (ChTx) and @entity19191 (IbTx), inhibited both the activated current and the KCa activity. In addition, on-cell patch recordings demonstrated an inwardly rectifying K+ channel, 21 +/- 1 pS at positive transmembrane potential (Vm) and 145 +/- 13 pS at negative Vm. @entity5217 (50 microM), @entity8594 (1 mM) and @entity4807 (100 microM) each inhibited the corresponding nonactivated, basal whole-cell current. Moreover, @entity5217 inhibited K+ channels in inside/out patches in a dose-dependent manner, and the IC50 = 46 microM. The identity of this K+ channel with an @entity855 -sensitive K+ channel (KATP) was confirmed by its inhibition with @entity855 (2 mM) and by its activation with @entity6335 (100 microM). We conclude that plasma membranes of HTB-9 cells contain the KCa and a lower conductance K+ channel with properties consistent with a @entity4136 receptor-linked KATP.

Membrane potassium channels and XXXX bladder tumor cells. I. Electrical properties.

@entity1 :: ('9606', 'Species') :: ['human'] @entity19191 :: ('MESH:C064719', 'Chemical') :: ['iberiotoxin'] @entity5217 :: ('MESH:D005905', 'Chemical') :: ['Glibenclamide', 'glibenclamide'] @entity6335 :: ('MESH:D003981', 'Chemical') :: ['diazoxide'] @entity189 :: ('MESH:D002277', 'Disease') :: ['carcinoma'] @entity8594 :: ('MESH:C080430', 'Chemical') :: ['Ba2+'] @entity4807 :: ('MESH:D011803', 'Chemical') :: ['quinine'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca(2+)'] @entity4136 :: ('CHEBI:26831', 'Chemical') :: ['sulfonylurea'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity1 :: (9606,Species) :: ['human']
