Hydrochlorothiazide ; pharmacology ; Pharmacogenetics

The primary object of this fundamental research was to survey the synergistic cardiovascular effects of iptakalim, a novel ATP-sensitive potassium channel (K(ATP)) opener, and clinical first-line antihypertensive drugs, such as calcium antagonists, thiazide diuretics and β receptor blockers by a 2 x 2 factorial-design experiment. It would provide a theoretical basis for the development of new combined antihypertensive therapy program after iptakalim is applied to the clinic. Amlodipine besylate, hydrochlorothiazide and propranolol were chosen as clinical first-line antihypertensive drugs. Blood pressure, heart rate (HR) and cardiac functions were observed in anesthetized normal rats by an eight-channel physiological recorder. The results showed that iptakalim monotherapy in a low dose could produce significant antihypertensive effect. There was no interaction between iptakalim and amlodipine on the maximal changes of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MABP), the left ventricular systolic pressure (LVSP), and the left ventricular end-diastolic pressure (LVEDP) (P > 0.05). However, the effects of combination iptakalim/amlodipine on the maximal changes of SBP, DBP, MABP, LVSP and LVEDP were more obvious than those of iptakalim or amlodipine monotherapy. And there was strong positive interaction between iptakalim and amlodipine on the maximal changes of HR (P>0.05). According to the maximal changes of DBP, MABP, LVSP and LVEDP (P < 0.05) of combination iptakalim with hydrochlorothiazide, there was strong positive interaction between them. But there was no interaction between iptakalim and hydrochlorothiazide on the maximal drop of SBP and HR (P > 0.05). According to the maximal drops of DBP, MABP of combination iptakalim with propranolol, there was strong positive interaction between them (P < 0.05). But there was no interaction between iptakalim and propranolol on the maximal changes of SBP, LVSP, LVEDP and HR (P > 0.05). In conclusion, it was the first time to study the effects of amlodipine, hydrochlorothiazide or propranolol, which had different mechanisms of action from iptakalim, on cardiovascular effects of iptakalim in anesthetized normal rats. This study proved that the combination of iptakalim with hydrochlorothiazide or propranolol respectively had significant synergism on lowering blood pressure, while the combination of iptakalim/amlodipine had additive action on lowering blood pressure. Meanwhile the antihypertensive effect was explicit, stable and long-lasting. Iptakalim thus appears suitable for the clinical treatment of hypertensive people who need two or more kinds of antihypertensive agents.
Amlodipine ; pharmacology ; Animals ; Antihypertensive Agents ; pharmacology ; Blood Pressure ; drug effects ; Drug Synergism ; Heart Rate ; Hydrochlorothiazide ; pharmacology ; Hypertension ; Propranolol ; pharmacology ; Propylamines ; pharmacology ; Rats

OBJECTIVEZanthoxylum heitzii is a medicinal plant widely used in central Africa for the treatment of many diseases, especially cardiovascular diseases and hypertension. The diuretic effects of crude stem bark extraction were determined and its safety in rats was evaluated.

METHODSThe diuretic effects of crude stem bark extraction of Z. heitzii 250 g ± 10 g) of both sexes. The crude stem bark extraction of Z. heitzii at the doses of 225, 300 and 375 mg/kg was administered to rats at 5 mL/kg body weight. Urine volume was determined 1, 2, 3, 4, 5, 6 and 24 h after administration of the extract. Kinetics of electrolyte elimination in response to a single oral administration dose of acute treatment was measured. The experiments were performed under the same conditions with two synthetic pharmacological diuretics considered as reference (furosemide and hydrochlorothiazide). Urinary and plasma concentrations of sodium and potassium ions were determined using flame photometry. Concentrations of creatinine, urea, glucose, albumin and electrolytes in the plasma and urine samples were evaluated using a two-way digital bidirectional spectrophotometer. The osmolarity of plasma and urine samples was measured by cytometry using an osmometer. Aldosterone was measured by radioimmunoassay.

RESULTSThe plant extract accelerated the elimination of overloaded fluid and increased urine volume and the excretion of Na+, K+ and Cl- 24 h after administration (P<0.05). The increase in elimination of Na+, K+, and Cl- induced by caused alkalinization of the urine, and showed a strong inhibitory effect on carbonic anhydrase and saluretic. These effects were mainly observed at the dose of 375 mg/kg. At the maximum diuretic response, urinary osmolarity decreased significantly (P<0.05) when compared to controls. The stability of aldosterone level, the absence of correlation with the plasma levels of Na+, and increased clearance of free water in the animals treated with indicated that increased diuresis and natriuresis were tubular in origin. No significant (P>0.05) changes were observed in the body temperature of the animals.

CONCLUSIONThe significant increase in urine volume 24 h after treatment followed a dose-response pattern. The excretion of Na+, K+ and Cl- caused a decrease in urine osmolarity. The stability of aldosterone, the absence of correlation with the plasma levels of sodium, and increased clearance of free water in animals treated with aqueous extract suggest that increased diuresis and moderate natriuresis elevation were of tubular origin.

Animals ; Carbonic Anhydrase Inhibitors ; pharmacology ; Diuretics ; pharmacology ; Electrolytes ; metabolism ; Female ; Furosemide ; pharmacology ; Hydrochlorothiazide ; pharmacology ; Kidney ; drug effects ; physiology ; Male ; Plant Bark ; Plant Extracts ; pharmacology ; Rats ; Rats, Wistar ; Zanthoxylum ; chemistry

OBJECTIVETo investigate effects of the furosemide, antisterone and hydrochlorothiazide on expression of kidney aquaporin-2 (AQP(2)) gene and urine aquaporin-2 excretion in rats.

METHODSForty SD rats were randomized into 4 groups, namely the control group, furosemide group, antisterone group and hydrochlorothiazide group with corresponding treatment. Blood and urine samples were collected from the rats for measurement of serum Na(+), urine volume and urine osmolality during medication. Semi-quantitative RT-PCR was performed to measure kidney inner medullary AQP(2) and vasopressin V(2)-R mRNA. Western blotting was employed to detect kidney inner medullary AQP(2) protein expression. Urine AQP(2) concentration was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTUrine volume and urinary AQP(2) excretion were both increased in rats treated with the 3 drugs as compared with that of the control group. However, urine osmolality was lower in furosemide group but higher inhydrochlorothiazide and antisterone groups than in the control group (P<0.05). The kidney inner medullary AQP(2) mRNA, V(2)-R mRNA and AQP(2) protein expression of furosemide group increased in comparison with that of the control group (Plt;0.05). In hydrochlorothiazide group, however, the above parameters were all decreased (Plt;0.05).

CONCLUSIONThe three classes of diuretics can all increase the excretion of the urinary AQP(2) but have different effects on the inner medullary AQP(2) mRNA and protein expression in normal rats. Hydrochlorothiazide reduces kidney AQP(2) mRNA and protein expression, while furosemide increased kidney AQP(2) gene expression.

Animals ; Aquaporin 2 ; genetics ; metabolism ; urine ; Blotting, Western ; Diuretics ; pharmacology ; Enzyme-Linked Immunosorbent Assay ; Furosemide ; pharmacology ; Gene Expression ; drug effects ; Hydrochlorothiazide ; pharmacology ; Kidney ; drug effects ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo evaluate the effect of CYP11B2 gene -344T/C polymorphism on renin-angiotensin-aldosterone system (RAAS) activity and blood pressure in response to hydrochlorothiazide (HCTZ) treatment in Han Chinese patients with essential hypertension.

METHODSEight hundred and twenty-nine patients with mild/moderate essential hypertensive were enrolled. All subjects had their antihypertensive medications withdrawn. After two weeks of wash-out period with placebo, each patient was given 12.5 mg of HCTZ per day for the next six weeks. Physical, biochemical measurements, and the activity of RAAS were taken at the end of the wash-out period (baseline) and 6-week diuretic therapy period. Changes in systolic and diastolic blood pressure were analyzed for association with interaction between genotypes at CYP11B2 -344T/C polymorphism and gender.

RESULTSA total of 776 patients completed the study. 17.5% of subjects have achieved blood pressure normalization after six weeks treatment. For male patients, the aldosterone level with CC genotype was significantly higher than that of those with TT or TC genotype. Following the HCTZ treatment, the blood pressure response in patients with CC genotype was less obvious than that in others, whilst the increase of aldosterone level was greater. For female patients, no association was found between CYP11B2 -344T/C polymorphism and aldosterone level. Following the HCTZ treatment, the blood pressure response in patients with CC genotype was greater than others, whilst the increase of aldosterone activity was less apparent.

CONCLUSIONIn males, the -344T/C polymorphism of CYP11B2 gene is associated with aldosterone level, and the change of aldosterone level was greater, the blood pressure response was weaker after HCTZ treatment. In females, there was no association between this polymorphism and aldosterone level. The change of aldosterone level and blood pressure response to HCTZ were different from that in males.

Antihypertensive Agents ; pharmacology ; Blood Pressure ; drug effects ; genetics ; Cytochrome P-450 CYP11B2 ; genetics ; Female ; Humans ; Hydrochlorothiazide ; pharmacology ; Hypertension ; drug therapy ; enzymology ; genetics ; Male ; Middle Aged ; Polymorphism, Genetic ; Renin-Angiotensin System ; drug effects ; genetics

To study the effects of major components of Maijunan tablets, puerarin (Pue) and rhynchophylline (Rhy) on the transport of hydrochlorothiazide (Hct) Caco-2 cell monolayer model, the transport parameters of Hct, such as apparent permeability coefficient (P(app) (B --> A) and P(app) (A --> B)) and the ratio of P(app) (B --> A) versus P(app) (A --> B), were studied and compared when Hct was used solely and co-used with Pue and/or Rhy. The effects of drug concentrations, conveying times, P-glyprotein (P-gp) inhibitor verapamil and conveying Liq pH values on the transport of Hct in the above conditions were also investigated. The results indicated that the absorption of Hct in Caco-2 cell monolayer model could be a carrier-mediated active transport, along with the excretion action mediated by P-gp. Pue can decrease the excretion action of Hct mediated by P-gp, and Rhy had no significant effect on the transport of Hct. The co-use of Hct, Pue and Rhy enhanced the absorption of Hct. Meanwhile, conveying Liq pH value had significant influence on the transport of Hct. The absorption of Hct at pH 6.0 was higher than that at pH 7.4.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; Absorption ; drug effects ; Biological Transport, Active ; drug effects ; Caco-2 Cells ; Drugs, Chinese Herbal ; administration & dosage ; isolation & purification ; pharmacology ; Humans ; Hydrochlorothiazide ; pharmacokinetics ; Hydrogen-Ion Concentration ; Indole Alkaloids ; administration & dosage ; isolation & purification ; pharmacology ; Isoflavones ; administration & dosage ; isolation & purification ; pharmacology ; Plants, Medicinal ; chemistry ; Time Factors ; Vasodilator Agents ; administration & dosage ; isolation & purification ; pharmacology ; Verapamil ; pharmacology

TRPV5 is believed to play an important role in the regulation of urinary calcium excretion. We assessed the effects of hydrochlorothiazide (HCTZ) on the expression of TRPV5, calbindin-D28K, and several sodium transporters in hypercalciuric rats. Sprague- Dawley rats were divided into 4 groups; control, HCTZ, high salt, and high salt with HCTZ group in experiment 1; control, HCTZ, high calcium (Ca), and high Ca with HCTZ group in experiment 2. To quantitate the expression of TRPV5, calbindin- D28K, and sodium transporters, western blotting was performed. In both experiments, HCTZ significantly decreased urinary calcium excretion. TRPV5 protein abundance decreased in all hypercalciuric rats, and restored by HCTZ in both high salt with HCTZ and high Ca with HCTZ group. Calbindin-D28K protein abundance increased in the high salt and high salt with HCTZ groups, but did not differ among groups in experiment 2. Protein abundance of NHE3 and NKCC2 decreased in all hypercalciuric rats, and were restored by HCTZ in only high Ca-induced hypercalciuric rats. In summary, protein abundance of TRPV5, NHE3, and NKCC2 decreased in all hypercalciuric rats. The hypocalciuric effect of HCTZ is associated with increased protein abundance of TRPV5 in high salt or calcium diet-induced hypercalciuric rats.
Animals ; Biological Transport ; Calcium/urine ; Calcium Channels/chemistry ; Calcium-Binding Protein, Vitamin D-Dependent/*biosynthesis ; Hydrochlorothiazide/pharmacology ; Hypercalciuria/*therapy ; Male ; Models, Biological ; Rats ; Rats, Sprague-Dawley ; Sodium/*metabolism ; Sodium-Hydrogen Antiporter/chemistry ; Sodium-Potassium-Chloride Symporters/metabolism ; TRPV Cation Channels/*biosynthesis/chemistry ; Thiazides/*pharmacology