It has been reported that a change in the cellular redox state may be involved in the regulation of vascular tone, but the underlying mechanism is not fully understood. The present study was designed to investigate the cellular effect of sulfhydryl modifying agents in the coronary artery of rabbit using the tension measurement and whole cell clamping method. The application of diamide, a sulfhydryl oxidizing agent, relaxed the endothelium denuded coronary arteries in a dose dependent manner. The fact that this diamide-induced relaxation was significantly attenuated by a pretreatment of 4-AP, and the coronary arteries precontracted with 100 mM K+ instead of histamine, suggests the involvement of 4-AP sensitive K+ channels in the diamide-induced relaxation of coronary arteries. Whole cell patch clamp studies revealed that the 4-AP sensitive IdK was significantly enhanced by the membrane permeant oxidizing agents, diamide and DTDP, and were reversed by subsequent exposure to the reducing agent, DTT. Neither the membrane impermeant oxidizing or reducing agents, GSSG or GSH, had any effect on the activity of IdK, indicating that intracellular sulfhydryl modification is critical for modulating IdK activity. The Diamide failed to significantly alter the voltage dependence of the activation and inactivation parameters, and did not change the inactivation process, suggesting that diamide increases the number of functional channels without altering their gating properties. Since IdK has been believed to play an important role in regulating membrane potential and arterial tone, our results about the effect of sulfhydryl modifying agents on coronary arterial tone and IdK activity should help understand the pathophysiology of the diseases, where oxidative damage has been implicated.
Animal ; Arteries/physiology ; Arteries/drug effects ; Arteries/cytology ; Coronary Vessels/physiology ; Coronary Vessels/drug effects* ; Coronary Vessels/cytology ; Female ; Male ; Oxidants/pharmacology* ; Potassium Channels/physiology ; Rabbits ; Reducing Agents/pharmacology* ; Sulfhydryl Compounds/metabolism*

OBJECTIVETo study the quantitative and functional changes of peripheral blood dendritic cells (DCs) and their subsets in the leukocyte population in patients with coronary artery disease (CHD) with different coronary artery plaques and explore the relation between DCs and coronary plaque development.

METHODSThirty CHD patients were divided into SAP (10 cases), UAP (10 cases) and ACS (10 cases) groups, with another 10 patients having negative result in coronary angiography as the control group. Intravascular ultrasound (IVUS) was performed to identify the nature of the plaques. The percentage and absolute number of peripheral blood DCs and DC subsets were measured by flow cytometry. The functional status of the DCs was analyzed by enzyme-linked immunosorbent assay (ELISA) and flow cytometry.

RESULTSIn the SAP group, IVUS found stable plaques in 8 cases and unstable plaques in 2 cases; in UAP group, 7 patients had unstable plaques, 2 had stable plaques, and 1 had plaque rupture. Plaque rupture, unstable plaques and stable plaques were found in 6, 3 and 1 patients in ACS group, respectively. In comparison with patients with stable plaques, those with unstable plaques had significantly increased percentages and number of DCs, mDCs and mDC1 (P<0.05), while the mDC2s and pDCs showed no obvious difference between them (P>0.05). The percentages and number of DCs, mDCs, mDC1s and pDCs were significantly decreased in patients with ruptured plaques (P<0.05). In peripheral blood monouclear cells cultured for 7 days, the CD83 expression was significantly higher in unstable and rupture plaque groups than in stable plaque group, and no significant difference was found between stable plaque group and the control group (P>0.05). In unstable and rupture plaque groups, co-culture with 2x10(5)/ml DCs evoked strong proliferation of the T cells in comparison with the stable plaque group, but no difference was found between the stable plaque and the control groups (P>0.05). Significantly higher levels of interleukin-2 and interferon-alpha were detected in the supernatant of the mixed lymphocyte reaction in unstable and ruptured plaque groups than in stable plaque and control groups, without obvious difference between the latter two groups.

CONCLUSIONThe percentage and absolute number of peripheral blood DCs and their functional status suggest the alterations of the coronary artery plaques in CHD patients.

Case-Control Studies ; Cells, Cultured ; Coronary Angiography ; Coronary Artery Disease ; immunology ; pathology ; Coronary Vessels ; pathology ; Dendritic Cells ; classification ; cytology ; immunology ; Female ; Flow Cytometry ; Humans ; Male

OBJECTIVETo investigate the distribution and mechanism of coronary arteriole (CA) cell resting membrane potential (RP) in guinea pigs.

METHODSCell RP was recorded by intracellular microelectrode in isolated guinea pig coronary arteriole (diameter < 100 microm).

RESULTS(1) Experiments were carried out in 112 cells with a mean RP of (-65 +/- 4.2)mV, the distribution of coronary arteriole cell RP fitted by Gaussian function was bimodal, one peak was -43 mV termed high RP, the other was -74 mV termed low RP. 10 mmol/L K+ and 3 micromol/ L acetylcholine(ACh) induced hyperpolarization in high-RP cells with (-7.4 +/- 0.87) mV (n = 13) and (-15 +/- 1.24) mV (n = 16) respectively, and induced depolarization in low-RP cells with (9.6 +/- 1.2) mV (n = 23) and (8.7 +/- 0.69) mV (n = 15) respectively. (2) The inward rectifier K+ channel (K(ir)) blocker Ba2+ caused concentration-dependent depolarization in low-RP cells with an EC50 of 120 micromol/L 100 micromol/L Ba2+ or higher could shift low-RP cells to high-RP state, the response of these cells to high K+ and ACh became a hyperpolarization.

CONCLUSIONThe distribution of coronary vascular cell RP is bimodal, high K+ and ACh induce different responses in low and high RP cells. The two RP states are exchangeable mainly due to all-or-none conductance changes of K(ir).

Acetylcholine ; metabolism ; Animals ; Arterioles ; cytology ; Coronary Vessels ; cytology ; physiology ; Female ; Guinea Pigs ; Male ; Membrane Potentials ; physiology ; Microelectrodes ; Myocardium ; metabolism ; Potassium Channels, Inwardly Rectifying ; physiology

OBJECTIVETo study the histopathologic features, differential diagnosis and pathogenesis of diabetic cardiomyopathy.

METHODSThe clinicopathologic features of 40 autopsy cases of diabetes mellitus were studied. The hearts from another 40 cases of non-diabetic elderly deceased were used for comparison.

RESULTSIn the 40 cases of diabetes studied, 36 cases (90.0%) showed microscopic myocardial cell death. Focal interstitial fibrosis was observed in 37 cases (92.5%). On the other hand, similar myocardial cell death and patchy interstitial fibrosis was seen in 8 cases (20.0%) and 9 cases (22.5%) of non-diabetic hearts, respectively. The difference between the two groups was statistically significant (P < 0.01). The mural thickness of intramyocardial blood vessels was significantly increased in diabetic group (20.6 microm +/- 4.2 microm) than in non-diabetic group (7.2 microm +/- 5.2 microm), P < 0.01.The myocardial changes in diabetic group however were similar to those in non-diabetic group with systemic hypertension.

CONCLUSIONSPathologic diagnosis of diabetic cardiomyopathy relies on detailed histologic examination of heart tissue and clinical correlation of a long history of diabetes mellitus. Exclusion of other possible etiologies is also essential. The myocardial cell death observed may be due to the ischemic effect induced by diabetic microangiopathy in cardiac muscle.

Aged ; Aged, 80 and over ; Autopsy ; Cardiomyopathies ; complications ; diagnosis ; Cell Death ; Coronary Vessels ; cytology ; pathology ; Diabetes Complications ; pathology ; Diagnosis, Differential ; Female ; Fibrosis ; diagnosis ; pathology ; Humans ; Male ; Myocardium ; cytology ; pathology

The aim of the present study was to examine the effects of tetramethylpyrazine (TMP) on large-conductance Ca(2+)-activated potassium channels (BK(Ca) channels) in porcine coronary artery smooth muscle cells, in order to provide the experimental evidence for expounding the mechanism of TMP in dilating coronary artery. Cell-attached and inside-out single channel recording techniques were used to observe the effects of TMP on BK(Ca) channels as well as the effects after the cells were treated by protein kinase A (PKA) inhibitor or protein kinase G (PKG) inhibitor. In inside-out patch, TMP activated BK(Ca) channels by increasing open-state probability (N(Po)) and decreasing close time (Tc) in a concentration-dependent manner. TMP (0.73~8.07 mmol/L) in the bath solution increased N(Po) from (0.01+/-0.003) to (0.03+/-0.01)~(1.21+/-0.18) (P<0.01, n=10), and decreased Tc from (732.33+/-90.67) ms to (359.67+/-41.30) ~ (2.96+/-0.52) ms (P<0.01, n=10). These actions of TMP occurred even when the free Ca(2+) concentration in the bath was reduced to ~ 0 mmol/L. The specific inhibitors of PKA (H-89, 3 mumol/L) and PKG (KT-5823, 1 mumol/L) had no influence on the activation of TMP on BK(Ca) channels. These findings suggest that TMP can directly activate BK(Ca) channels in coronary artery smooth muscle, which probably is an important mechanism in dilating coronary artery.
Animals ; Coronary Vessels ; cytology ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Patch-Clamp Techniques ; Potassium Channels, Calcium-Activated ; drug effects ; physiology ; Pyrazines ; pharmacology ; Swine ; Vasodilator Agents ; pharmacology

Spontaneous transient outward currents (STOCs) play an important role in the myogenic regulation of small artery tone, such as coronary artery. In the present study, we investigated the electrophysiological properties and the regulation of STOCs in vascular smooth muscle cells (VSMCs) of porcine coronary artery by perforated patch-clamp technique. Our data showed that STOCs were dependent on voltage and extracellular calcium and they were highly variable in amplitudes and frequencies. STOCs superimposed stochastically onto whole-cell K(+) currents induced by step and ramp protocols. STOCs were completely abolished by ChTX [inhibitor of large-conductance Ca(2+)-activated potassium (BK(Ca)) channels], removal of extracellular Ca(2+), or addition of ryanodine (50 mumol/L) respectively. In contrast, CdCl2 and verapamil, inhibitors of voltage-dependent L-type Ca(2+) channels, had little effect on STOCs. Caffeine (5 mmol/L) transiently increased STOCs (hump), followed by a temporary inhibition. Ca(2+) ionophore A23187 increased both amplitude and frequency of STOCs. Na(+) ionophore monensin increased the frequency of STOCs. STOCs were strongly inhibited by KB-R7943, a selective inhibitor of the reverse mode of the Na(+)/Ca(2+) exchanger. Based on these observations, we conclude that STOCs are mediated by BK(Ca) channels. The generation and activation of STOCs depend upon Ca(2+) influx through Na(+)/Ca(2+) exchange and release of Ca(2+) from sarcoplasmic reticulum (SR) via ryanodine receptors. This suggests that Na(+)/Ca(2+) exchange determines calcium store refilling. Recycling of entering Ca(2+) from superficial SR may locally elevate Ca(2+) concentration at the plasma membrane, thereby activating BK(Ca) channels and then initiating STOCs.
Animals ; Coronary Vessels ; cytology ; physiology ; Electrophysiological Phenomena ; physiology ; Muscle, Smooth, Vascular ; cytology ; physiology ; Myocytes, Smooth Muscle ; cytology ; physiology ; Patch-Clamp Techniques ; Potassium Channels, Calcium-Activated ; physiology ; Sodium-Calcium Exchanger ; physiology ; Swine

D-myo-inositol 1,4,5-trisphosphate (IP(3)) plays an important role in signal transduction. It releases Ca(2+) from intracellular sites, which activates the Ca(2+)-dependent channels such as large-conductance Ca(2+)-activated potassium channels (BK channels). The present study was therefore designed to determine if the activity of BK channels in porcine coronary artery smooth muscle cells was increased by IP(3). Using the inside-out patch-clamp technique, the activity of single BK channels was recorded in porcine coronary artery smooth muscle cells. In excised inside-out membrane patches, IP(3) (10-50 micromol/L) enhanced the open probability (Po) of BK channels in a dose-dependent manner in the intracellular side of inside-out patches and its effect was almost completely abolished by washout. The open-state probability of the BK channels increased from a control level of 0.0402+/-0.0152 to 0.1365+/-0.0212 (20 micromol/L IP(3)) and 0.1865+/-0.0175 (30 micromol/L IP(3)). IP(3) decreased the mean close time markedly, but had no effect on the amplitude of BK channels. The activation of IP(3) on BK channels did not decline. The metabolite of IP(3) had no obvious effect on BK channels. This study provides evidence that IP(3) activates BK channels in porcine coronary artery smooth muscle cells in a dose-dependence manner.
Animals ; Coronary Vessels ; cytology ; metabolism ; Inositol 1,4,5-Trisphosphate ; physiology ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism ; Muscle, Smooth, Vascular ; metabolism ; Swine ; Vasodilation ; physiology

To determine applicability of the cryopreservation procedure for vessel grafts, the viability of endothelial cells (ECs) among the whole cells in three kinds of organs artery, vein, trachea in mongrel dogs was evaluated on the basis of histological analysis. The Griffonia simplicifolia agglutins-fluorescein isothiocyanate (GSA-FITC) and propidium iodide (PI) double staining methods were combined with flow cytometry (FCM), which was able to simultaneously determine the viability of whole cells and ECs from the same tissue, were performed after harvesting, after antibiotic solution treatment, and after cryopreservation and thawing. In most cases, the viability of ECs is lower than that of whole cells from veins and arteries. The viability of whole cells in veins was maintained until the antibiotic solution treatment and then decreased significantly after cryopreservation and thawing, while the ECs began to decrease significantly after the antibiotic solution treatment and more markedly decreased after thawing. The viability of ECs and whole cells from arteries was similar to that of the veins' conditions. The viability of whole cells from the trachea decreased with a similar pattern to that of the ECs from vessels. In consideration of maintaining cell viability among the three kinds of organs, the viability of arteries was better than that of the others. The cells in the trachea demonstrated a lower viability than the vessels. The effect of antibiotic solution treatment on the reduction of cell viability depends on the treatment time and temperature.
Animalt ; Arteries/transplantation ; Cell Survival ; Coronary Vessels*/transplantatione ; Cryopreservation* ; Dogs ; Endothelium, Vascular/physiology* ; Endothelium, Vascular/cytology ; Female ; Male ; Trachea*/transplantation ; Middle Age ; Veins/transplantation

The aim of the present study was to explore the effect of nitric oxide (NO) on iron-induced toxicity in rat hearts. Langendorff perfused rat heart and enzymatically isolated cardiomyocytes were used. It was shown that lipophilic Fe-HQ reduced the contractile amplitude, velocity and end-diastolic cell length in the cardiomyocyte, while the left ventricular developed pressure (LVDP), +/-dp/dt(max), heart rate and coronary flow showed biphasic alterations, which increased in the first 2 min and then was followed by a decline in isolated perfused rat heart; the contents of lactate dehydrogenase (LDH) and creatine kinase (CK) in the coronary effluent and the malondialdehyde (MDA) in the myocardium were increased. L-arginine (L-Arg), an NO precursor, reduced the contractile amplitude and end-diastolic cell length in the cardiomyocyte; but reversibly increased LVDP, +/-dp/dt(max), and coronary flow in isolated perfused rat heart. Pretreatment with L-Arg aggravated the Fe-HQ-induced decrease in contractile amplitude, velocity and end-diastolic cell length in the cardiomyocyte; LVDP, +/-dp/dt(max), heart rate and coronary flow were significantly reduced in the perfused heart, and the levels of LDH and CK increased in the coronary effluent. In contrast, the NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) blocked the Fe-HQ induced change in contractile amplitude, velocity and end-diastolic cell length in the cardio- myocyte; it inhibited the decrease in LVDP, LVEDP and +/-dp/dt(max), and reduced the LDH and CK. Removing endothelial cells in coronary vessels attenuated the increase in LVDP and +/-dp/dt(max) at the beginning of Fe-HQ perfusion. It is suggested that L-Arg aggravates the iron-induced cardiac dysfunction, NO can mediate the iron-induced toxicity in heart, and endothelial cells in coronary vessels play an important role in the early stage of the effect of iron.
Animals ; Arginine ; pharmacology ; Coronary Vessels ; cytology ; Creatine Kinase ; metabolism ; Endothelial Cells ; drug effects ; Heart ; drug effects ; Iron ; toxicity ; L-Lactate Dehydrogenase ; metabolism ; Malondialdehyde ; metabolism ; Myocardium ; metabolism ; Myocytes, Cardiac ; cytology ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; metabolism ; Rats

OBJECTIVEThe present study was to explore signaling mechanisms underlying nicotine-induced inhibition of large-conductance calcium-activated potassium channels (BK(Ca)).

METHODS8 week male Wistar rats were divided randomly into saline group and nicotine group and received respectively injection with saline or nicotine (Sigma, Shanghai, China) at 2 mg/(kg x d) for 21 days. Coronary vascular smooth muscle cells were dissociated enzymatically. Dissociated smooth muscle cells were interfered with CPT-cAMP (100 micromol/L) or forskolin (10 micromol/L). The signal channel open dwell-time (To), close dwell-time (Tc) and open probability (Po) were recorded.

RESULTSCPT-cAMP or forskolin significantly prolonged To, shorten Tc and increased Po in saline group (P < 0.01). But in nicotine group To, Tc and Po did not been changed.

CONCLUSIONThis phenomenon may serve as a physiological mechanism that nicotine inhibits BK(Ca) channel activity to increase via cAMP/PKA-dependent pathway.

Animals ; Arteries ; cytology ; drug effects ; metabolism ; Coronary Vessels ; cytology ; drug effects ; metabolism ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism ; Male ; Myocytes, Smooth Muscle ; drug effects ; metabolism ; Nicotine ; pharmacology ; Patch-Clamp Techniques ; Rats ; Rats, Wistar ; Signal Transduction