Endogenous nitric oxide(NO) plays an important role in the regulation of blood pressure. It has been known that the evoked NO-dependent dilator system may be impaired in various hypertensive models. The effects of NG-nitro-L-arginine(L-NNA), lipopolysaccharide(LPS) and tempol on mean arterial pressure(MAP) and the effects of L-NNA on isolated aorta tone were studied in order to elucidate potential alterations in resting vasodilator tone of NO in two-kidney, one clip(2K1C) hypertension. Plasma nitrite/nitrate levels were measured by colorimetric assay, and the expression of endothelial and inducible NO synthases(eNOS, iNOS) was determined by Western blot analysis. L-NNA caused an increase of MAP, while LPS produced a hypotensive effect in both 2K1C and control rats. The magnitude of the pressor or depressor response to L-NNA and LPS was comparable in the two groups. Tempol induced a sustained decrease in MAP in 2K1C rats, while it had no effects on MAP in control rats. Plasma concentrations of NO metabolites were significantly increased following the LPS-treatment in both 2K1C and control rats, while they were not affected by tempol-treatment. In endothelium-intact aortic rings precontracted with 25 mM KCl, L-NNA caused a dose-dependent contraction. The magnitude of the maximal contraction was attenuated in 2K1C rats as compared with control. An inhibition of contractile responses to L-NNA in the hypertensive group was also shown in rubbed rings, although the magnitude of contractions was markedly reduced. The vascular expression of both eNOS and iNOS was significantly decreased in 2K1C rats as compared with control. These results indicate that 2K1C hypertension is associated with a reduced basal vasodilator tone of NO and a decrease in the vascular expression of NOS isozymes.
Animals ; Aorta ; Blood Pressure ; Blotting, Western ; Hypertension ; Isoenzymes ; Nitric Oxide* ; Plasma ; Rats*

The monitoring of airway inflammation has assessed in bronchial asthma directly by sputum examination, and indirectly by measurements in peripheral blood. To investigate the diagnostic value of these two methods, we compared nitric oxide (NO) metabolites, eosinophils, and eosinophil cationic protein (ECP) in sputum and blood in patients with asthma and control subjects. Sputum and serum were obtained from fifteen patients with asthma, and then were examined before anti-asthma treatment, including steroid preparations. ECP was measured by fluoroimmunoassay. NO metabolites were assayed by using modified Griess reaction. Asthmatic patients, compared with control subjects, had significantly higher level of NO metabolites, higher proportion of eosinophils, and higher levels of ECP in sputum. Asthmatic patients, compared with control subjects, however, had significantly higher number of eosinophils, and were at higher levels of ECP in blood. FEV1, FEV1 /FVC was negatively correlated with sputum eosinophils. The area under receiver operating characteristic(ROC) curve showed that eosinophils in sputum are significantly accurate markers than NO metabolites in sputum and blood. These findings suggest that the proportion of eosinophils in sputum have more accurate diagnostic marker of asthmatic airway inflammation than NO metabolites in sputum in differentiating asthmatic patients from control subjects.
Adult ; Area Under Curve ; Asthma/*blood/*metabolism ; Blood Proteins/*metabolism ; Comparative Study ; Eosinophils/*metabolism ; Female ; Fluoroimmunoassay ; Human ; Inflammation ; Male ; Nitrates/metabolism ; Nitric Oxide/blood/*metabolism ; Nitrites/metabolism ; ROC Curve ; Ribonucleases/blood/*metabolism ; Sputum/*metabolism

BACKGROUND AND OBJECTIVES: Protein tyrosine kinases appear to be involved in the signal transduction mechanisms, which result in vascular smooth muscle contraction, as well those required in cell growth. The present study was conducted to examine the role of tyrosine kinases in the norepinephrine-induced vascular smooth muscle contraction of isolated aortae from two-kidney, one clip (2K1C) hypertensive rats. MATERIALS AND METHODS: 2K1C hypertension was made by clipping the left renal artery of the rats, with age-matched rats receiving a sham treatment serving as controls. Thoracic aortae denuded of endothelium were mounted in tissue baths to measure the isometric tension. RESULTS: The putative tyrosine kinase inhibitors, genistein and tyrphostin 25, significantly inhibited the contractile responses of the aorta to norepinephrine in the control rats, but not in the 2K1C rats. The protein tyrosine phosphatase inhibitor, sodium orthovanadate, selectively potentiated the contractile response to norepinephrine, but only in the controls. Genistein, tyrphostin 25 and sodium orthovanadate did not affect KCl-induced vascular contractions in either the 2K1C or the controls. The vascular contraction elicited by phorbol 12, 13 dibutyrate, in the presence and absence of genistein, did not alter in either the 2K1C or the controls. CONCLUSION: These findings indicate that protein tyrosine kinases participate in the norepinephrine-induced contraction of rat aortic smooth muscle, where the role is attenuated in 2K1C renal hypertension.
Animals ; Aorta ; Aorta, Thoracic ; Baths ; Endothelium ; Genistein ; Hypertension ; Hypertension, Renal ; Muscle, Smooth ; Muscle, Smooth, Vascular ; Norepinephrine ; Phosphotransferases* ; Placebos ; Protein Tyrosine Phosphatases ; Protein-Tyrosine Kinases ; Rats* ; Renal Artery ; Signal Transduction ; Sodium ; Tyrosine* ; Vanadates

PURPOSE: The present study was aimed to examine whether caffeine alters the local regulation of atrial natriuretic peptide(ANP) and nitric oxide(NO) systems in the kidney. METHODS: Male Sprague-Dawley rats were treated with caffeine, consisting of a single oral bolus(0.2%, 1 mL/kg) followed by supplementation in drinking water(0.2%) for 1 day. Rats treated the same without caffeine served as control. The tissue expression of ANP mRNA was determined by reverse transcription-polymerase chain reaction. Tissue levels of nitrite/nitrate were determined. The expression of aquaporin(AQP)-1 and AQP2 proteins was determined by Western blot analysis. RESULTS: Following the treatment with caffeine, the expression of ANP mRNA was increased in the kidney. The renal tissue nitrite/nitrate level was also increased by caffeine-treatment. On the other hand, the expression of AQP1 and AQP2 proteins was not significantly altered. CONCLUSION: The enhanced activities of local ANP and NO systems may in part be causally related with the caffeine-induced natriuresis and diuresis, while AQP channels are not involved.
Animals ; Aquaporin 2 ; Atrial Natriuretic Factor ; Blotting, Western ; Caffeine* ; Diuresis ; Drinking ; Hand ; Humans ; Kidney ; Male ; Natriuresis ; Nitric Oxide* ; Rats* ; Rats, Sprague-Dawley ; RNA, Messenger

BACKGROUND: Although being associated with an elevated plasma atrial natriuretic peptide(ANP), its precise role in the postobstructive diuresis has not been fully understood. Evidence has been provided suggesting that the locally-synthesized ANP in the kidney contributes to the regulation of urinary sodium excretion. The present study was aimed to investigate whether an altered regulation of local ANP system is involved in the postobstructive diuresis. METHODS: Male Sprague-Dawley rats were used. Both proximal ureters were ligated for 48 hours, after which the kidneys were taken without releasing the ligature, being designated as bilateral ureteral obstruction(BUO) group; or the ligature was released and 4 or 24 hr later, urinary data were collected, being designated as BUR-4 or BUR-24, respectively. Sham operated rats were used as control. Plasma ANP levels were determined by radioimmunoassay. The expression of ANP and natriuretic peptide receptor(NPR)-A mRNAs was determined by reverse transcription-polymerase chain reaction(RT-PCR). To further examine whether the altered renal ANP system, if any, was associated with an altered biological effects of guanylyl cyclase, ANP-stimulated cGMP accumulation was determined in membrane preparations of the glomeruli and papillae by radioimmunoassay. RESULTS: The plasma ANP level was increased in BUO group compared with that in the control(260.5+/-32.5 vs. 133.3+/-23.5pg/mL, p<0.05), decreased in BUR-4 group(3.6+/-0.5 vs. 143.5+/-42.8pg/mL, p<0.01), while not significantly different in BUR-24 group. In BUR-4. the urinary flow rate increased compared with that in the control(1598+/-370 vs. 215+/-34 microL/hr, p<0.01), along with increases of FENa(11.5+/-4.1 vs. 0.25+/-0.02%, p<0.05) and UNaV (153.7+/-23.7 vs. 36.5+/-9.3microEq/hr, p<0.01). In BUR-24, the urinary parameters were normalized. Renal tissue expression of ANP mRNA was increased in BUO as well as in BUR-4, while not changed in BUR-24. NPR-A mRNA expression was decreased in the kidney of BUO. The ANP-stimulated accumulation of cGMP in the isolated glomeruli and papillae in BUO was significantly reduced. The guanylyl cyclase activities were partly recovered in BUR-4 and completely in BUR-24. CONCLUSION: An enhanced local activity of ANP in the kidney may be causally related to the postobstructive diuresis.
Animals ; Atrial Natriuretic Factor ; Diuresis ; Guanylate Cyclase ; Humans ; Kidney* ; Ligation ; Male ; Membranes ; Plasma ; Radioimmunoassay ; Rats* ; Rats, Sprague-Dawley ; RNA, Messenger ; Sodium ; Ureter

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease. There are some reports in the literature concerning unilateral ADPKD. However, in adults, only a few cases of unilateral ADPKD with agenesis of contralateral kidney have been reported. We present a case of unilateral ADPKD with agenesis of contralateral kidney in a 66-yr-old man. Radiographic images showed the enlarged right kidney with multiple variable-sized cysts and the absence of the left kidney. The diagnosis of ADPKD was confirmed by the family screening. The patient received maintenance hemodialysis for endstage renal disease. We report a case of unilateral ADPKD associated with contralateral renal agenesis in a 66-yr-old male patient with a literature review.
Abdomen/pathology ; Aged ; Female ; Human ; Kidney/abnormalities* ; Male ; Pedigree ; Polycystic Kidney, Autosomal Dominant/diagnosis* ; Polycystic Kidney, Autosomal Dominant/pathology* ; Polycystic Kidney, Autosomal Dominant/physiopathology ; Radiopharmaceuticals/metabolism ; Technetium Tc 99m Dimercaptosuccinic Acid/metabolism

Gitelman's syndrome is a variant of Bartter's syndrome characterized by hypocalciuria and hypomagnesemia. The administration of thiazide diuretics may induce a subnormal increase of urinary Na+ and Cl- excretion in patients with Gitelman's syndrome, consistent with the hypothesis that less Na+ and Cl- than normal is reabsorbed by the thiazide-inhibitable transporter in Gitelman's syndrome. Specific mutations of NaCl cotransporter, coupled with mutant NaCl cotransporter expression studies clearly demonstrated that many of the characteristics of individuals with Gitelman's syndrome are explained by lack of function of NaCl cotransporter. We recently diagnosed a patient with Gitelman's syndrome by performing the thiazide and furosemide tests, and it is suggested that the clearance studies by diuretic administration may be of diagnostic help in Gitelman's syndrome.
Adolescent ; Bartter Syndrome/*diagnosis/metabolism/physiopathology ; *Benzothiadiazines ; Chlorides/blood/urine ; Diuretics/diagnostic use ; Electrolytes/blood/urine ; Female ; Furosemide/diagnostic use ; Humans ; Kidney/*physiopathology ; Kidney Function Tests ; Sodium/blood/urine ; Sodium Chloride Symporter Inhibitors/*diagnostic use ; Sodium Chloride Symporters ; Symporters/metabolism ; Syndrome

BACKGROUND: The plant-derived estrogen biochanin A is known to cause vasodilation, but its mechanism of action in hypertension remains unclear. This study was undertaken to investigate the effects and mechanisms of biochanin A on the thoracic aorta in two-kidney, one clip (2K1C) renovascular hypertensive rats. METHODS: Hypertension was induced by clipping the left renal artery, and control age-matched rats were sham treated. Thoracic aortae were mounted in tissue baths to measure isometric tension. RESULTS: Biochanin A caused concentration-dependent relaxation in aortic rings from 2K1C hypertensive and sham-treated rats, which was greater in 2K1C rats than in sham rats. Biochanin A-induced relaxation was significantly attenuated by removing the endothelium in aortic rings from 2K1C rats, but not in sham rats. Nomega-Nitro-L-arginine methylester, a nitric oxide synthase inhibitor, or indomethacin, a cyclooxygenase inhibitor, did not affect the biochanin A-induced relaxation in aortic rings from 2K1C and sham rats. By contrast, treatment with glibenclamide, a selective inhibitor of adenosine triphosphate-sensitive K+ channels, ortetraethy-lammonium, an inhibitor of Ca2+-activated K+ channels, significantly reduced biochanin A-induced relaxation in aortic rings from both groups. However, 4-aminopyridine, a selective inhibitor of voltage-dependent K+ channels, inhibited the relaxation induced by biochanin A in 2K1C rats, whereas no significant differences were observed in sham rats. CONCLUSION: These results suggest that the enhanced relaxation caused by biochanin A in aortic rings from hypertensive rats is endothelium dependent. Vascular smooth muscle K+ channels may be involved in biochanin A-induced relaxation in aortae from hypertensive and normotensive rats. In addition, an endothelium-derived activation of voltage-dependent K+ channels contributes, at least in part, to the relaxant effect of biochanin A in renovascular hypertension.
4-Aminopyridine ; Adenosine ; Animals ; Aorta ; Aorta, Thoracic ; Baths ; Endothelium ; Estrogens ; Glyburide ; Hypertension ; Hypertension, Renovascular ; Indomethacin ; Muscle, Smooth, Vascular ; Nitric Oxide Synthase ; Phytoestrogens* ; Potassium Channels, Calcium-Activated ; Prostaglandin-Endoperoxide Synthases ; Rats* ; Relaxation ; Renal Artery ; Vasodilation*

It is well known that the endothelium plays an important role in the circulation by modulating contractile responses of vascular smooth muscle. This study was designed to investigate the alterations and the mechanisms of endothelial modulation in chronic 2-kidney, 1 clip(2K1C) hypertensive rats. 2K1C hypertension was made by clipping the left renal artery and age-matched control rats received a sham treatment. Aortic rings were mounted in tissue baths for measurement of isometric tension. In rings with endothelium, norepinephrine evoked concentration-dependent contraction. Endothelium removal markedly enhanced the contraction, and the responses were less pronounced in 2K1C rats than control rats. Similar fashion of the contractions by endothelium removal was observed with norepinephrine and the alpha1 drenoceptor agonist phenylephrine in control rats, while phenylephrine did not alter the contraction by endothelium removal in 2K1C rats. The alpha2 drenoceptor agonist clonidine also greatly enhanced the contraction after endothelium removal, however the endothelial inhibition was still shown in 2K1C rats. In contrast to norepinephrine-induced contractions, the enhancement of serotonin-or prostaglandin F2alpha - induced contractions after endothelium removal was small and similar in 2K1C and control rats. NG-nitro-L-arginine methyl ester enhanced the contraction induced by agonists in aortic rings with endothelium, which was similar to the response in rings without endothelium. The relaxation response to acetylcholine was attenuated in 2K1C rats, while the response to sodium nitroprusside remained unaltered. These results indicate the endothelium plays an inhibitory role against contractions in rat aorta by releasing nitric oxide, but the characteristics of the endothelial inhibition are not identical against various agonists. The negative endothelial modulation is more pronounced during alpha1 and alpha2 renoceptor- mediated contractions than during contractions mediated by other receptors. In addition, the inhibitory role of the endothelium against alpha1 drenoceptor agonist-induced contraction is impaired in 2K1C renal hypertension.
Acetylcholine ; Animals ; Aorta ; Baths ; Clonidine ; Dinoprost ; Endothelium ; Hypertension ; Hypertension, Renal ; Muscle, Smooth, Vascular ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Nitroprusside ; Norepinephrine ; Phenylephrine ; Placebos ; Rats* ; Relaxation ; Renal Artery ; Vasoconstriction*

Recent discovery of aquaporin(AQP) water channels has advanced our understanding of water transport in the kidney. They play an important role in the urinary concentration through generation of medullary hypertonicity and regulation of collecting duct water permeability. Among multiple isoforms of AQP family, AQP1 is highly expressed in the proximal tubule and descending thin limb. The critical role of AQP1 has been confirmed in transgenic mice lacking AQP1 that are unable to concentrate the urine and severely dehydrated. The abundance of AQP2 is highly expressed in the principal cell of the collecting duct. It is short-term and long-term regulated by AVP/cAMP pathway to increase the osmotic water reabsorption. The short-term regulation of AQP2 channels occurs as a result of an exocytic insertion of the cytoplasmic AQP2 vesicles into the apical membrane, whereas the long-term effect is to increase the total abundance of AQP2 proteins. Water reabsorption across the basolateral membrane of the collecting duct is in turn mediated by AQP3 and AQP4. An altered regulation of AQP channels in the kidney has been known in various pathophysiological situations. A reduced abundance of AQP water channels may at least in part account for the impaired urinary concentration in the ischemic acute renal failure and cisplatin-, gentamicin-, and amphotericin B-induced nephropathy. The postobstructive diuresis has been attributed to a decreased expression of AQP1-4 proteins in the obstructed kidney. In these situations, however, the primary impairment in the pathway leading to the generation of cAMP and hence the expression of cAMP-mediated AQP chan nels lies at the level of G proteins and/or at the catalytic unit of adenylyl cyclase. On the other hand, following the treatment with deoxycorticosterone or NG-nitro-L-arginine methyl ester, the expression of AQP2 proteins was increased in the kidney, in association with an augmented adenylyl cyclase activity. In two-kidney, one clip hypertension, the total abundance of AQP2 proteins was significantly decreased in the clipped kidney, while their trafficking remained unaltered. Concomitantly with the reversal of the blood pressure following removal of the renal arterial clip, the abundance of AQP2 expression returned to the control level. The AVP-evoked cAMP generation was decreased in the clipped kidney, and returned to the control value following removal of the clip. Following the treatment with 0.04% methimazole, the expression of AQP2 protein was increased in the kidney, in association with hyponatremia. An altered regulation of AQP water channels in the kidney may be causally related to various pathophysiological situations associated with altered urinary concentration ability and water retention.
Mice ; Rats ; Animals