Regulatory volume decrease (RVD) is essential for the survival of animal cells. The aim of this study was to observe the RVD process in rat ventricular myocytes, and to determine if the KATP channels are involved in the RVD process in these cells. By using reverse transcriptase polymerase chain reaction and Western blot analysis, we demonstrated that there are two types of KATP channels expressed in rat ventricular myocytes: Kir6.1 and Kir6.2. When rat cardiac myocytes were exposed to hypotonic solution, cell volume increased significantly within 15 min and then gradually recovered. This typical RVD process could be inhibited by a Cl– channel blocker (0.5 mM 9-anthracene-carboxylic acid , 9-AC), a K+ channel blocker (5.0 mM CsCl) and a KATP channel blocker glibenclamide (10 μM). Electrophysiological results showed that hypotonic solution activated a whole-cell current, which had similar biophysical characteristics with KATP opener (pinacidil)-induced currents. This current could be blocked by glibenclamide. Our data suggested that the RVD process in rat ventricular myocytes is dependent on the activation of K+ channels, and that KATP channels are involved in this process., L. Shi ... [et al.]., and Obsahuje seznam literatury
Monoaminergic neurotransmitter 5-hydroxytryptamine (5-HT), also known as serotonin, plays im portant roles in modulating the function of the olfactory system. However, thus far, the knowledge about 5-HT and its receptors in olfactory receptor neurons (ORNs) and their physiological role have not been fully characterized. In the present study, reverse transcription- polymerase chain reaction (RT-PCR) analysis revealed the presence of 5-HT 1A and 5-HT 1B receptor subtypes in mouse olfactory epithelium at the mRNA level. With subtype selective antibodies and standard immunohistochemical techniques, both receptor subtypes were found to be positively labeled. To further elucidate the molecular mechanisms of 5-HT act on the peripheral olfactory transduction, the whole-cell patch clamp techniques were used on freshly isolated ORNs. We found that 5-HT decreased the magnitude of outward K + current in a dose- dependent manner and these inhi bitory effects were markedly attenuated by the 5-HT 1A receptor blocker WAY-100635 and the 5-HT 1B receptor antagonist GR55562. These data suggested that 5-HT may play a role in the modu lation of peripheral olfactory signals by regulating outward potassium currents, both 5-HT 1A and 5-HT 1B receptors were involved in this regulation., S. Gao, ... [et al.]., and Obsahuje seznam literatury