Role of cerebral ATP-sensitive K+ channels in arterial pressure regulation during acute cerebral ischaemia in SHR and WKY rats

The cardiovascular effects of central hydrogen sulfide are related to K(ATP) channels activation

Hydrogen sulfide (H(2)S), an endogenous "gasotransmitter", exists in the central nervous system. However, the central cardiovascular effects of endogenous H(2)S are not fully determined. The present study was designed to investigate the central cardiovascular effects and its possible mechanism in anesthetized rats. Intracerebroventricular (icv) injection of NaHS (0.17~17 microg) produced a significant and dose-dependent decrease in blood pressure (BP) and heart rate (HR) (P < 0.05) compared to control. The higher dose of NaHS (17 microg, n = 6) decreased BP and HR quickly of rats and 2 of them died of respiratory paralyse. Icv injection of the cystathionine beta-synthetase (CBS) activator s-adenosyl-L-methionine (SAM, 26 microg) also produced a significant hypotension and bradycardia, which were similar to the results of icv injection of NaHS. Furthermore, the hypotension and bradycardia induced by icv NaHS were effectively attenuated by pretreatment with the K(ATP) channel blocker glibenclamide but not with the CBS inhibitor hydroxylamine. The present study suggests that icv injection of NaHS produces hypotension and bradycardia, which is dependent on the K(ATP) channel activation.

Patents related to therapeutic activation of K(ATP) and K(2P) potassium channels for neuroprotection: ischemic/hypoxic/anoxic injury and general anesthetics

BACKGROUND

Mechanisms of neuroprotection encompass energy deficits in brain arising from insufficient oxygen and glucose levels following respiratory failure; ischemia or stroke, which produce metabolic stresses that lead to unconsciousness and seizures; and the effects of general anesthetics. Foremost among those K(+) channels viewed as important for neuroprotection are ATP-sensitive (K(ATP)) channels, which belong to the family of inwardly rectifying K(+) channels (K(ir)) and contain a sulfonylurea subunit (SUR1 or SUR2) combined with either K(ir)6.1 (KCNJ8) or K(ir)6.2 (KCNJ11) channel pore-forming alpha-subunits, and various members of the tandem two-pore or background (K(2P)) K(+) channel family, including K(2P)1.1 (KCNK1 or TWIK1), K(2P)2.1 (KCNK2 or TREK/TREK1), K(2P)3.1 (KCNK3 or TASK), K(2P)4.1 (KCNK4 or TRAAK), and K(2P)10.1 (KCNK10 or TREK2).

OBJECTIVES

This review covers patents and patent applications related to inventions of therapeutics, compound screening methods and diagnostics, including K(ATP) channel openers and blockers, as well as K(ATP) and K(2P) nucleic/amino acid sequences and proteins, vectors, transformed cells and transgenic animals. Although the focus of this patent review is on brain and neuroprotection, patents covering inventions of K(ATP) channel openers for cardioprotection, diabetes mellitus and obesity, where relevant, are addressed.

RESULTS/CONCLUSIONS

Overall, an important emerging therapeutic mechanism underlying neuroprotection is activation/opening of K(ATP) and K(2P) channels. To this end substantial progress has been made in identifying and patenting agents that target K(ATP) channels. However, current K(2P) channels patents encompass compound screening and diagnostics methodologies, reflecting an earlier 'discovery' stage (target identification/validation) than K(ATP) in the drug development pipeline; this reveals a wide-open field for the discovery and development of K(2P)-targeting compounds.