Molecular cloning and expression of a bovine endothelial inward rectifier potassium channel 1The nucleotide sequence data reported in this paper has been submitted to GenBank with Accession Number U95369.1

AbstractA 5.1 kb cDNA encoding an inward rectifier K+ channel (BIK) was isolated from a bovine aortic endothelial cell library. The cDNA codes for a 427-amino-acid protein with two putative transmembrane regions. Sequence analysis reveals that BIK is a member of the Kir2.1 family of inward rectifier K+ channels. Expression in Xenopus oocytes showed that BIK is a K+-specific strong inward rectifier channel that is sensitive to extracellular Ba2+, Cs+, and a variety of anti-arrhythmic agents. Northern analysis revealed that endothelial cells express a 5.5 kb BIK mRNA that is sensitive to shear stress

Shear stress regulates the endothelial Kir2.1 ion channel

Endothelial cells (ECs) line the mammalian vascular system and respond to the hemodynamic stimulus of fluid shear stress, the frictional force produced by blood flow. When ECs are exposed to shear stress, one of the fastest responses is an increase of K(+) conductance, which suggests that ion channels are involved in the early shear stress response. Here we show that an applied shear stress induces a K(+) ion current in cells expressing the endothelial Kir2.1 channel. This ion current shares the properties of the shear-induced current found in ECs. In addition, the shear current induction can be specifically prevented by tyrosine kinase inhibition. Our findings identify the Kir2.1 channel as an early component of the endothelial shear response mechanism

At least two mRNA species contribute to the properties of rat brain A-type potassium channel expressed in xenopus oocytes

Fast transient K⁺ channels (A channels) of the type operating in the subthreshold region for Na⁺ action potential generation were expressed in Kenopus oocytes injected with rat brain poly(A) RNA. Sucrose gradient fractionation of the RNA separates mRNAs encoding A-currents (6–7 kb) from mRNAs encoding other voltage-dependent K⁺ channels. A-currents expressed with fractionated mRNA differ in kineticsAnd pharmacology from A-currents expressed with total mRNA. The original properties of the A-currents can be reconstituted when small mRNAs (2–4 kb) are added to the large mRNA fraction. Thus the properties of the A-currents expressed with total poly(A) RNA depend on the presence of more than one mRNA species. mRNA(s) present in the large RNA fraction must encode channel subunits since they express an A-current by themselves. The small mRNA(s) may encode a second subunit(s) or a factor, such as an enzymatic activity that modulates the properties of the channels, which could play a role in generating A-channel functional diversity

At least two mRNA species contribute to the properties of rat brain A-type potassium channel expressed in xenopus oocytes

Fast transient K⁺ channels (A channels) of the type operating in the subthreshold region for Na⁺ action potential generation were expressed in Kenopus oocytes injected with rat brain poly(A) RNA. Sucrose gradient fractionation of the RNA separates mRNAs encoding A-currents (6–7 kb) from mRNAs encoding other voltage-dependent K⁺ channels. A-currents expressed with fractionated mRNA differ in kineticsAnd pharmacology from A-currents expressed with total mRNA. The original properties of the A-currents can be reconstituted when small mRNAs (2–4 kb) are added to the large mRNA fraction. Thus the properties of the A-currents expressed with total poly(A) RNA depend on the presence of more than one mRNA species. mRNA(s) present in the large RNA fraction must encode channel subunits since they express an A-current by themselves. The small mRNA(s) may encode a second subunit(s) or a factor, such as an enzymatic activity that modulates the properties of the channels, which could play a role in generating A-channel functional diversity