Kidney diseases are important causes of mortality world widely. Renal microvascular dysfunction plays a pivotal role in the development of kidney diseases. Pharmacological and biochemical tools have been used to conduct detailed studies on the metabolization of arachidonic acid by cytochrome P450 (CYP450) in renal microvasculature. CYP450 epoxygenase metabolites epoxyeicosatrienoic acids (EETs) are mainly produced in renal microvessels. EETs exhibit renoprotective effects through vasodilation, anti-hypertension, anti-apoptosis and anti-inflammation, and were reported as therapeutic targets of renal diseases. However, the ability of the kidney in generating EETs is reduced in renal diseases. Recently, the studies from transgenic animal overexpressing CYP450 epoxygenases and application of soluble epoxide hydrolase inhibitors revealed that increasing of EETs exhibits renoprotective effects in vivo. The present review focuses on the protective mechanisms of EETs in kidney physiology and diseases.
Animals ; Animals, Genetically Modified ; Arachidonic Acid ; metabolism ; Cytochrome P-450 Enzyme System ; physiology ; Disease Models, Animal ; Humans ; Inflammation ; Kidney ; physiology ; Kidney Diseases ; physiopathology ; Vasodilation

OBJECTIVETo study the effect of gastrodin on isolated thoracic aorta rings of rats and to investigate the potential mechanism.

METHODSA perfusion model of isolated thoracic aorta rings of rats was applied. The effect of cumulative gastrodin (5, 50, 100,150, 200, and 250 μmol/L) on endothelium-intact aorta rings was investigated. The same procedure was applied to observe the effect of gastrodin on endothelium-intact/denuded aorta rings pre-contracted with 10(-6) mol/L phenylephrine hydrochloride (PE). The aorta rings incubated by 200 mmol/L gastrodin in the Ca(2+)-free (K-H) solution was contracted by using PE. The effect of 200 mmol/L gastrodin on endothelium-denuded aorta rings pre-contracted with 60 mmol/L KCl was also observed.

RESULTSCompared with the denuded gastrodin group, the intact gastrodin group could significantly relax the PE-contracted aorta rings (P<0.01). In Ca(2+)-free (K-H) solution KHS, the PE-induced contraction rate of aorta rings pre-incubated by gastrodin was 6.5%±0.7%, which was significantly less than the control group (11.8%±0.9%,P<0.01). However, after 3 mmol/L CaCl2 was added, the Ca(2+)-induced contraction in the gastrodin group (51.7%±2.4%) was similar to that in the control group (49.8%±2.8%). The contractile rate of rings in the KCl-contracted gastrodin group (96.3%±0.6%) was not significantly different from that in the control group (96.8%±1.2%).

CONCLUSIONSGastrodin has the effect of vasorelaxation on isolated thoracic aorta rings of rats. The mechanism of the vasorelaxation of gastrodin may mainly work through the inhibition of inositol 1, 4, 5-trisphosphosphate receptor on the sarcoplasmic reticulum of the arterial smooth muscle, which leads to the reduction of the Ca(2+) released from the sarcoplasmic reticulum.

Animals ; Aorta, Thoracic ; drug effects ; physiology ; Benzyl Alcohols ; pharmacology ; Calcium ; metabolism ; Endothelium, Vascular ; physiology ; Female ; Glucosides ; pharmacology ; In Vitro Techniques ; Male ; Phenylephrine ; pharmacology ; Rats ; Rats, Wistar ; Vasodilation ; drug effects

Scutellarin (SCU), a flavonoid from a traditional Chinese medicinal plant. Our previous study has demonstrated that SCU relaxes mouse aortic arteries mainly in an endothelium-depend-ent manner. In the present study, we investigated the vasoprotective effects of SCU against HR-induced endothelial dysfunction (ED) in isolated rat CA and the possible mechanisms involving cyclic guanosine monophosphate (cGMP) dependent protein kinase (PKG). The isolated endothelium-intact and endothelium-denuded rat CA rings were treated with HR injury. Evaluation of endothelium-dependent and -independent vasodilation relaxation of the CA rings were performed using wire myography and the protein expressions were assayed by Western blotting. SCU (10-1 000 μmol·L(-1)) could relax the endothelium-intact CA rings but not endothelium-denuded ones. In the intact CA rings, the PKG inhibitor, Rp-8-Br-cGMPS (PKGI-rp, 4 μmol·L(-1)), significantly blocked SCU (10-1 000 μmol·L(-1))-induced relaxation. The NO synthase (NOS) inhibitor, NO-nitro-L-arginine methylester (L-NAME, 100 μmol·L(-1)), did not significantly change the effects of SCU (10-1 000 μmol·L(-1)). HR treatment significantly impaired ACh-induced relaxation, which was reversed by pre-incubation with SCU (500 μmol·L(-1)), while HR treatment did not altered NTG-induced vasodilation. PKGI-rp (4 μmol·L(-1)) blocked the protective effects of SCU in HR-treated CA rings. Additionally, HR treatment reduced phosphorylated vasodilator-stimulated phosphoprotein (p-VASP, phosphorylated product of PKG), which was reversed by SCU pre-incubation, suggesting that SCU activated PKG phosphorylation against HR injury. SCU induces CA vasodilation in an endothelium-dependent manner to and repairs HR-induced impairment via activation of PKG signaling pathway.
Animals ; Apigenin ; pharmacology ; Cell Adhesion Molecules ; drug effects ; Cell Hypoxia ; Coronary Vessels ; drug effects ; Cyclic GMP ; analogs & derivatives ; metabolism ; pharmacology ; Cyclic GMP-Dependent Protein Kinases ; Glucuronates ; pharmacology ; Microfilament Proteins ; drug effects ; NG-Nitroarginine Methyl Ester ; metabolism ; pharmacology ; Phosphoproteins ; drug effects ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; complications ; physiopathology ; Signal Transduction ; drug effects ; Thionucleotides ; metabolism ; pharmacology ; Vasodilation ; drug effects ; physiology

Spontaneous, rhythmical contractions, or vasomotion, can be recorded from cerebral vessels under both normal physiological and pathophysiological conditions. We investigated the cellular mechanisms underlying vasomotion in the cerebral basilar artery (BA) of Wistar rats. Pressure myograph video microscopy was used to study the changes in cerebral artery vessel diameter. The main results of this study were as follows: (1) The diameters of BA and middle cerebral artery (MCA) were 314.5±15.7 μm (n=15) and 233.3±10.1 μm (n=12) at 10 mmHg working pressure (P<0.05), respectively. Pressure-induced vasomotion occurred in BA (22/28, 78.6%), but not in MCA (4/31, 12.9%) from 0 to 70 mmHg working pressure. As is typical for vasomotion, the contractile phase of the response was more rapid than the relaxation phase; (2) The frequency of vasomotion response and the diameter were gradually increased in BA from 0 to 70 mmHg working pressure. The amplitude of the rhythmic contractions was relatively constant once stable conditions were achieved. The frequency of contractions was variable and the highest value was 16.7±4.7 (n=13) per 10 min at 60 mmHg working pressure; (3) The pressure-induced vasomotion of the isolated BA was attenuated by nifedipine, NFA, 18β-GA, TEA or in Ca(2+)-free medium. Nifedipine, NFA, 18β-GA or Ca(2+)-free medium not only dampened vasomotion, but also kept BA in relaxation state. In contrasts, TEA kept BA in contraction state. These results suggest that the pressure-induced vasomotion of the isolated BA results from an interaction between Ca(2+)-activated Cl(-) channels (CaCCs) currents and K(Ca) currents. We hypothesize that vasomotion of BA depends on the depolarizing of the vascular smooth muscle cells (VSMCs) to activate CaCCs. Depolarization in turn activates voltage-dependent Ca(2+) channels, synchronizing contractions of adjacent cells through influx of extracellular calcium and the flow of calcium through gap junctions. Subsequent calcium-induced calcium release from ryanodine-sensitive stores activates K(Ca) channels and hyperpolarizes VSMCs, which provides a negative feedback loop for regenerating the contractile cycle.
Animals ; Basilar Artery ; cytology ; metabolism ; physiology ; Chloride Channels ; metabolism ; Female ; Male ; Membrane Potentials ; physiology ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Myocytes, Smooth Muscle ; cytology ; metabolism ; Potassium Channels, Calcium-Activated ; metabolism ; Rats ; Rats, Wistar ; Vasoconstriction ; physiology ; Vasodilation ; physiology

OBJECTIVEIn our study, the function of the third-order branches of the mesentenc artery was measured by microvascular ring technique, which can be used to detect microvascular function in some disease related to microvascular dysfunction.

METHODSIsolated, fixed, standardized and then activated the third-order branches of rat mesenteric artery. Microvascular tone was measured by systolic and diastolic drags respectively, with the help of DMT tension apparatus and PowerLab data acquisition system.

RESULTSThe third-order branches of rat mesenteric artery showed excellent response to vasoactive drugs. The contraction effect of norepinephrine (NE) reached 19 in mN. When acetylcholine (Ach) or sodium nitroprusside (SNP) of 10(9)-10(5)mol/L was added, vascular tones showed gradient drop: 80% of maximal relaxation when adding ACh, while 95% of maximal relaxation when adding SNP.

CONCLUSIONThe third-order branches of the mesenteric artery function was successfully detected by using microvascular ring technique.

Acetylcholine ; pharmacology ; Animals ; In Vitro Techniques ; Male ; Mesenteric Arteries ; drug effects ; physiology ; Nitroprusside ; pharmacology ; Norepinephrine ; pharmacology ; Rats ; Vasoconstrictor Agents ; pharmacology ; Vasodilation ; physiology ; Vasodilator Agents ; pharmacology

OBJECTIVETo investigate the changes of vasoconstriction and vasodilatation under different temperature conditions and the protective effects of Vitamin E (Vit E) against endothelial injury induced by hypothermia.

METHODSThe tail arterial rings were prepared for isometric tension recording using multi wire myograph system. The effect of temperature on relaxation and construction was evaluated. Incubate the arterial rings with different concentration of Vit E when they were exposed to hypothermia, then acetylcholine (ACh)-induced endothelium-dependent relaxation was investigated to evaluate the activity of endothelial.

RESULTS(1) The hypothermia could enhanced the dose-dependent construction induced by PE in mice tail artery. (2) Exposure to hypothermia also resulted in increase of sodium nitroprusside (SNP)-induced re-After incubation with Vit E, the vascular relaxation responses to ACh increased in an endothelium-dependent manner, when compared with the hypothermia-treated group.

CONCLUSIONThe vascular function of constriction was attenuated by hypothermia, while the relaxation was increased. Vit E could prevent the hypothermia-induced decrease in vascular endothelial cells.

Animals ; Arteries ; drug effects ; physiology ; Cold Temperature ; Hypothermia ; In Vitro Techniques ; Male ; Mice ; Prazosin ; pharmacology ; Solanaceous Alkaloids ; pharmacology ; Vasoconstriction ; drug effects ; Vasodilation ; drug effects ; Vasodilator Agents ; pharmacology ; Vitamin E ; pharmacology

This study investigated the role of calcium-activated Cl⁻ channels (CaCCs) in mediating vasomotor activity of cerebral basilar artery (BA) of Wistar rat. Pressure myograph was used to examine the changes in diameter of isolated BA to vasoactive reagents. The results showed that (1) The rate of pressure-induced vasomotor activity was 78.6% (n = 28) in BA from 0 to 100 mmHg working pressure. The contractile phase of the response was faster than the relaxation phase; (2) The amplitude of contraction was (62.6 ± 6.4) µm (n = 22), the frequency of contraction was variable and the highest value was 8.0 ± 2.3 per 5 min at 60 mmHg working pressure (n = 22); (3) The pressure-induced vasomotor activity of BA was markedly attenuated when Ca²⁺ was removed from medium; (4) The pressure-induced vasomotor activity was blocked by voltage dependent Ca²⁺ channel blocker nimodipine; (5) The pressure-induced vasomotor was inhibited by CaCC antagonists NFA and NPPB. These results suggest that the pressure-induced vasomotor activity of isolated BA is associated with Ca²⁺ influx that activates CaCCs.
Animals ; Basilar Artery ; physiology ; Calcium ; physiology ; Chloride Channels ; physiology ; Rats ; Rats, Wistar ; Vasoconstriction ; Vasodilation

The aim of the present study was to investigate the roles of calcium-activated chloride channels (Cl(Ca)) in the two-phase hypoxic pulmonary vasoconstriction (HPV). The second pulmonary artery branches were dissected from male Sprague-Dawley rats, and the changes in vascular tone were measured by using routine blood vascular perfusion in vitro. The result showed that, under normoxic conditions, Cl(Ca) inhibitors (NFA and IAA-94) significantly relaxed second pulmonary artery contracted by norepinephrine (P < 0.01), but merely had effects on KCl-induced second pulmonary artery contractions. A biphasic contraction response was induced in second pulmonary artery ring pre-contracted with norepinephrine exposed to hypoxic conditions for at least one hour, but no biphasic contraction was observed in pulmonary rings pre-contracted with KCl. NFA and IAA-94 significantly attenuated phase II sustained hypoxic contraction (P < 0.01), and also attenuated phase I vasodilation, but had little effect on phase I contraction. These results suggest that Cl(Ca) is an important component forming phase II contraction in secondary pulmonary artery, but not involved in phase I contraction.
Animals ; Chloride Channels ; physiology ; Glycolates ; pharmacology ; Hypoxia ; physiopathology ; Male ; Norepinephrine ; pharmacology ; Pulmonary Artery ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Vasoconstriction ; Vasodilation

Adenosine was identified as a regulator of skeletal muscle blood flow almost 50 years ago. It was first proposed that increased use of ATP during muscle contractions led to net ATP breakdown, and its breakdown product, adenosine, diffused through the interstitial space to the blood stream to be washed away. En-route to its removal, adenosine was suggested to relax the vascular smooth muscle, thereby increasing the blood flow and oxygen supply to the contracting muscle. This mechanism has been researched quite intensively over the years, yet there are still many aspects that remain unclear. It has been confirmed that adenosine does, indeed, relax vascular smooth muscle and contribute to exercise hyperaemia, but the discovery that adenosine was formed extracellularly has shifted the research focus onto its precursor, ATP. ATP is released from many tissues, and produces many effects, including both vasodilation and vasoconstriction, as well as modulation of the neural mechanisms for skeletal muscle blood flow control. This review summarizes the current state of knowledge on the contributions of adenosine and ATP to the skeletal muscle vasodilation that accompanies contractile activity.
Adenosine ; physiology ; Adenosine Triphosphate ; physiology ; Exercise ; physiology ; Hemodynamics ; Humans ; Muscle Contraction ; Muscle, Skeletal ; blood supply ; Muscle, Smooth, Vascular ; physiology ; Regional Blood Flow ; physiology ; Vasoconstriction ; Vasodilation

OBJECTIVETo investigate the vasodilating effect of capsaicin (CAP) on rat mesenteric artery and its mechanism.

METHODSThe third branch of the superior mesenteric artery in male Sprague-Dawley rat (250-350 g) was excised, the periadventitial fat and connective tissue were removed and the mesenteric artery was dissected into 2 mm rings. Each ring was placed in a 5 ml organ bath of DMT 610M system and the tension was recorded.

RESULTSCAP (10(-9)-10(-5) mol/L) relaxed endothelium-intact and endothelium-denuded mesenteric artery pre-constricted by phenylephrine (10(-5) mol/L), and the vasodilation in endothelium-intact mesenteric artery was stronger than that in endothelium-denuded one. Pretreatment with either L-NAME (3 X10(-4) mol/L), an inhibitor of nitric oxide synthase(NOS), or CGRP8-37 (2 X 10(-6) mol/L), an antagonist of calcitonin gene-related peptide (CGRP), for 30 min significantly attenuated the relaxation of endothelium-intact mesenteric artery induced by CAP. CGRP (10(-10)-3 X10(-8) mol/L) relaxed endothelium-intact and endothelium-denuded mesenteric artery pre-constricted by phenylephrine, and the vasodilation in endothelium-intact mesenteric artery was stronger than that in endothelium-denuded one. Substance P did not relax the mesenteric artery pre-constricted by phenylephrine.

CONCLUSIONCAP has partial endothelium-dependent relaxation effect on rat mesenteric artery, which may be mediated by activating the endothelial NOS-NO pathway. The endothelium-independent relaxation in rat mesenteric artery induced by CAP may be mediated by CGRP.

Animals ; Calcitonin Gene-Related Peptide ; metabolism ; Capsaicin ; pharmacology ; In Vitro Techniques ; Male ; Mesenteric Arteries ; drug effects ; physiology ; Peptide Fragments ; metabolism ; Rats ; Rats, Sprague-Dawley ; Vasodilation ; drug effects