OBJECTIVETo investigate the changes in aorta morphology and Ca(2+)-activated K(+) (KCa) channel expression in the diabetic rats.

METHODSA diabetic rat model was established by a single intraperitoneal injection of streptozotocin (30 mg/kg) after a modified high fat and glucose diet for 8 weeks. Pathological changes in the aorta were observed with HE staining, elastic fiber staining, Masson's trichrome staining and immunohistochemistry. Both the mRNA and protein levels of KCa channels in the aorta were measured by RT-PCR and Western blotting.

RESULTSEarly atherosclerotic changes were observed in the aorta wall of the diabetic rats. The mRNA and protein levels of KCa1.1 channel α- and β-subunits were significantly decreased, while the expression of KCa3.1 channels was obviously enhanced in the middle layer of the aorta in the diabetic rats.

CONCLUSIONKCa channel switching in smooth muscles may play a role in the development of atherosclerosis in diabetic rats.

Animals ; Aorta ; pathology ; Atherosclerosis ; pathology ; Diabetes Mellitus, Experimental ; pathology ; Intermediate-Conductance Calcium-Activated Potassium Channels ; metabolism ; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits ; metabolism ; Male ; Muscle, Smooth, Vascular ; metabolism ; Rats ; Rats, Sprague-Dawley

AIMTo investigate the changes of large-conductance calcium-activated potassium channels (BKCa, MaxiK) during aging and relations between the changes and blood pressure.

METHODSMale spontaneously hypertensive rats (SHR) aged 9, 15, 21, 27, 33 weeks (the number of each weeks SHR was 4) were selected as hypertension group rats, corresponding gender, weeks and number Wistar-Kyoto rats (WKY) as control group rats. Blood pressure of abdominalis aorta of each weeks SHR and WKY were measured by BL-420F experimental system of biological function. The arteria mesenteric minor (AMM) were isolated in blunt dissection method. The vascular smooth muscle cells (VSMCs) of AMM were isolated with prolease. The potassium current, the current after BKCa were blockaded by Tetraethylammonium (TEA) and the capacitance of membrane (Cm) of VSMCs of AMM were recorded with using whole cell patch clamp, and calculated the BKCa current and the BKCa current density. Probe the correlation of the changes of BKCa current density with MABP during aging.

RESULTSThe potassium current density and BKCa current density of VSMCs of AMM of SHR were decreasing during aging, however, the changes of WKY had no statistically significance (P > 0.05). The BKCa current density was extremely correlative with MABP in SH R (the values of r were -0.7174), in WKY, the BKCa current density was correlative with MAB P r = -0.4832.

CONCLUSIONBKCa current and current density attenuate with aging, the level of blood pressure is response of the attenuated degree. The BKCa current density is extremely correlative with the blood pressure.

Aging ; physiology ; Animals ; Blood Pressure ; physiology ; Cell Membrane ; physiology ; Hypertension ; metabolism ; physiopathology ; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism ; physiology ; Male ; Membrane Potentials ; physiology ; Mesenteric Arteries ; cytology ; Muscle, Smooth, Vascular ; cytology ; metabolism ; physiology ; Patch-Clamp Techniques ; Potassium Channels ; metabolism ; physiology ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY

OBJECTIVETo investigate the impact of the BKCa channel in prostate smooth muscle cells (PSMCs) on the membrane potential in SD rats with chronic abacterial prostatitis (CAP).

METHODSCAP models were established in 20 SD rats by castration and injection of 17 beta-estrogen, and another 20 were taken as normal controls. PSMCs were cultured and purified in vitro, and treated with DiBAC4, followed by quantitative observations on the dynamic changes of the cell membrane potential by laser confocal microscopy.

RESULTSThe extracellular calcium ion concentration ([Ca2+]o) was increased and the BKCa channel was activated, which induced the hyperpolarization of the PSMC membrane in both the CAP models and normal control rats. This effect was weakened with Iberiotoxin (IbTX), a specific blocker of the BKCa channel, but the amplitude of the hyperpolarization was obviously lower in the CAP than in the control group. The DiBAC4 fluorescence intensity induced by hyperpolarization was 18.78 +/- 2.92 in the former and 38.85 +/- 7.10 in the latter (P < 0.05), while that induced by IbTX was 1.61 +/- 0.46 and 6.12 +/- 1.32 (P < 0.05), respectively.

CONCLUSIONSignificant decrease of BKCa-mediated hyperpolarization in the CAP model can reduce its abilities of regulating the membrane potential and suppressing the excessive contraction of PSMCs, which may result in pelvic pain syndrome and lower urinary tract symptoms.

Animals ; Cells, Cultured ; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits ; Male ; Membrane Potentials ; Myocytes, Smooth Muscle ; cytology ; metabolism ; Potassium Channels ; metabolism ; Prostate ; cytology ; Prostatitis ; metabolism ; physiopathology ; Rats ; Rats, Sprague-Dawley

Arrhythmias, Cardiac ; Humans ; Large-Conductance Calcium-Activated Potassium Channels ; Small-Conductance Calcium-Activated Potassium Channels

OBJECTIVETo investigate the effect of exercise stress on chronic cigarette smoking induced downregulation of large conductance calcium-activated potassium channel (BKca) and voltage-dependent delayed rectifier potassium channel (Kv1.5) expression in pulmonary arterial smooth muscle cells of rats.

METHODSRats were divided into three groups: the normal control group, the smoking control group and the smoking + exercise group. The plasma cortisol level, the potassium channel expression and the pathological changes in lung tissue were determined with HE staining, the immunohistochemistry and the in-situ hybridization.

RESULTS(1) In the smoking + exercise group, the plasma cortisol level was determined immediately after exercise [(1528.7 +/- 469.7) ng/L] and was higher than that determined before exercise [(672.4 +/- 235.7) ng/L] (P < 0.01); (2) The HE staining showed that the chronic pulmonary inflammatory response in the smoking control group was severe while it was mild in the smoking + exercise group; (3) The mRNA and protein expression (OD value) of BKca in the smoking control group (mRNA: 0.2206 +/- 0.0415 for big artery and 0.3935 +/- 0.1378 for small artery; protein: 0.2634 +/- 0.1219 for big artery and 0.0995 +/- 0.0851 for small artery) were less than those in the normal control group. The mRNA expression of BKca in the smoking + exercise group (OD value) (0.5022 +/- 0.1134 for big artery and 0.6408 +/- 0.2135 for small artery) was higher than that in the smoking control group; (4) The mRNA and protein expression of Kv1.5 in the smoking control group (OD value) (mRNA: 0.9354 +/- 0.3290 for big artery and 0.5012 +/- 0.1170 for small artery; protein: 1.1112 +/- 0.3310 for big artery and 0.4736 +/- 0.1250 for small artery) were less than those in the normal control group. The protein expression of Kv1.5 in the smoking + exercise group (0.7445 +/- 0.2690) in small artery was higher than that in the smoking control group.

CONCLUSIONProper exercise stress can decrease inhibition effect of the chronic smoking on the expression of potassium channel BKca and Kv1.5, which perhaps partly results from exercise induced increase of cortisol secretion.

Animals ; Down-Regulation ; Hydrocortisone ; blood ; Kv1.5 Potassium Channel ; biosynthesis ; genetics ; Large-Conductance Calcium-Activated Potassium Channel alpha Subunits ; Male ; Movement ; physiology ; Muscle, Smooth, Vascular ; metabolism ; Potassium Channels ; biosynthesis ; genetics ; Pulmonary Artery ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Smoking ; adverse effects

Humans ; Hypertension ; Large-Conductance Calcium-Activated Potassium Channels

Humans ; Large-Conductance Calcium-Activated Potassium Channels ; TRPC Cation Channels ; Vasodilation

PURPOSE: This study was performed to determine the effects of phytoestrogen on seminal vesicle excitability. MATERIALS AND METHODS: Single smooth muscle cells of seminal vesicle were obtained from rabbits using proteolytic enzymes(collagenase). Using single cell and channel recording methods of patch clamp, the various currents of potassium channels in smooth muscle cells were recorded. Potassium currents were divided into calcium dependent and independent. RESULTS: Most of the calcium dependent K currents were maxi-K currents and most of calcium independent ones were delayed rectifier K currents. Inside-out patch clamp technique was used to characterize the maxi-K channel. The channel showed outward rectification and calcium dependency. The single-channel conductance of this channel estimated from slope conductance was 119.4+/-11.7 pS under physiological conditions. These characteristics were typical properties of maxi-K channels. Application of genistein(10micronM) rarely affected the delayed rectifier K channel activities, but it evoked significant increase of maxi-K channel activities at both single cell and channel levels. CONCLUSIONS: From these results it is strongly suggested that the excitability and contractility of seminal vesicle might be modulated by genistein through a mechanism of maxi-K channel activation.
Calcium ; Genistein ; Large-Conductance Calcium-Activated Potassium Channels ; Muscle, Smooth* ; Myocytes, Smooth Muscle* ; Phytoestrogens* ; Potassium Channels* ; Potassium* ; Rabbits ; Seminal Vesicles*

PURPOSE: Recent studies have shown that potassium (K+) and sodium channels are involved in prostate cell growth. However, a great many of the studies have been done in prostate cancer cell lines and there are only scant studies on prostate cancer and benign prostatic hypertrophy (BPH) tissue. The present study was aimed to evaluate the alterations of the calcium-activated K+ channel (KCa) expression in prostate cancer, and to compare them with the expression profiles in human BPH tissue to understand their potential role in the progression of prostate cancer. MATERIALS AND METHODS: The prostate tissues obtained from radical prostatectomy (n=10) and transurethral resection of the prostate (n=18) were quickly frozen in liquid nitrogen for the RNA measurements. The protein and mRNA levels of the KCa subtypes and connexins were measured by performing immunoblot analysis and reverse-transcription polymerase chain reaction, respectively. RESULTS: The mRNA levels of type 2 (SK2) and type 3 (SK3) small-conductance and large-conductance (BK) KCas in the prostate cancer tissues were decreased more than 50% compared with those in the BPH samples. In addition, the BK and SK2 protein levels in prostate cancer were also significantly lower than those in the BPH. As reported previously, the connexin 26 and 43 transcript signals in the prostate cancer were significantly reduced compared with those in the BPH samples. CONCLUSIONS: These results suggest that the impaired expression of KCas may have a role in tumor progression via aberrant and uncontrolled prostate cell growth.
Cell Line ; Connexins ; Humans* ; Large-Conductance Calcium-Activated Potassium Channels ; Nitrogen ; Polymerase Chain Reaction ; Potassium ; Potassium Channels, Calcium-Activated* ; Prostate* ; Prostatectomy ; Prostatic Hyperplasia ; Prostatic Neoplasms* ; RNA ; RNA, Messenger ; Small-Conductance Calcium-Activated Potassium Channels ; Sodium Channels

OBJECTIVETo explore the mechanisms of the influx of calcium ions during the activation of ACh-sensitive BK channel (big conductance, calcium-dependent potassium channel) in type II vestibular hair cells of guinea pigs.

METHODSType II vestibular hair cells were isolated by collagenase type IA. Under the whole-cell patch mode, the sensitivity of ACh-sensitive BK current to the calcium channels blockers was investigated, the pharmacological property of L-type calcium channel activator-sensitive current and ACh-sensitive BK current was compared.

RESULTSFollowing application of ACh, type II vestibular hair cells displayed a sustained outward potassium current, with a reversal potential of (-70.5 +/- 10.6) mV (x +/- s, n = 10). At the holding potential of -50 mV, the current amplitude of ACh-sensitive potassium current activated by 100 micromol/L ACh was (267 +/- 106) pA (n = 11). ACh-sensitive potassium current was potently sensitive to the BK current blocker, IBTX (iberiotoxin, 200 nmol/L). Apamin, the well-known small conductance, calcium-dependent potassium current blocker, failed to inhibit the amplitude of ACh-sensitive potassium current at a dose of 1 micromol/L. ACh-sensitive BK current was sensitive to NiCl2 and potently inhibited by CdCl2. NiCl2 and CdCl2 showed a dose-dependent blocking effect with a half inhibition-maximal response of (135.5 +/- 18.5) micromol/L (n = 7) and (23.4 +/- 2.6) micromol/L (n = 7). The L-type calcium channel activator, (-) -Bay-K 8644 (10 micromol /L), mimicked the role of ACh and activated the IBTX-sensitive outward current.

CONCLUSIONACh-sensitive BK and L-type calcium channels are co-located in type II vestibular hair cells of guinea pigs.

Animals ; Calcium Channels, L-Type ; Guinea Pigs ; Hair Cells, Vestibular ; metabolism ; Large-Conductance Calcium-Activated Potassium Channels ; Patch-Clamp Techniques