Page 48 - F. Cell biology

[F. Cell biology-28]

Cortisone Increases Human Kv1.5 Channel Currents

Soobeen Hwang¹, Su-Hyun Jo¹

¹Physiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Korea, ²BIT Medical

Convergence, Kangwon National University, Chuncheon 200-701, Korea

Glucocorticoids are the primary hormones that respond to stress and protect organisms from dangerous situations.
The glucocorticoids hydrocortisone dormant form, cortisone, affect the cardiovascular system with changes such as

increased blood pressure and cardio protection. Kv1.5 channels are expressed in the heart and pancreatic beta-cells.

The most studied is the human Kv1.5 channel (hKv1.5), which is thought to underlie the ultra-rapidly activating
delayed rectifier K+ current Ikur found in human atrial myocytes. We examined the effect of cortisone on the human
Kv1.5 channel using a Xenopus oocyte expression system and a two-microelectrode voltage clamp technique.

Cortisone increase the amplitude of the Kv1.5 channel current in a concentration-dependent manner. Cortisone
inhibited Kv1.5 currents, eliminating the possibility of genomic regulation. Rate of increase was concentration-

dependent and voltage-dependent. Rate of increase for peak and steady state currents were significantly different
at 0~+10mV voltage we examined. These results suggested that cortisone increase Kv1.5 currents via a non-genomic

mechanism, providing a mechanism for the possible arrhythmogenic effects of cortisone.