Effects of glucose supplementation on the pharmacokinetics of intravenous chlorzoxazone in rats with water deprivation for 72 h

Excessive amount of lactose in the diet of two-week-old calves induces urinary protein changes

Abstract. The present paper was undertaken to analyse and identify urinary proteins that were significantly altered in urine of calves in response to short-term administration of milk replacer with lactose addition. We used 2-D electrophoresis combined with matrix-assisted laser desorption/ionisation and time-of-flight (MALDI-TOF) mass spectrometry. Of all spots analysed, four showed significantly decreased abundance: alpha-1-antiproteinase (A1AT), serotransferrin (TF), sex hormone-binding globulin (SHBG) and cytochrome P450 2E1 (CYP2E1). One displayed an increased abundance: adenosine triphosphate (ATP)-citrate synthase. The changes in abundance of SHBG and CYP2E1 proteins were caused by the direct effect of an oversupply of sugar, while A1AT, TF and ATP-citrate synthase showed altered abundance probably due to indirect effects. The results of this study confirmed that calves' urine is a very precious biological material to evaluate the renal function, and it may be valuable in veterinary and zootechnical diagnostics.

Prenatal dehydration alters renin-angiotensin system associated with angiotensin-increased blood pressure in young offspring

The renin-angiotensin system (RAS) has an important role in cardiovascular homeostasis. This study determined the influence of water deprivation during pregnancy on the development of the RAS in rats, and examined blood pressure (BP) in the adolescent offspring. Pregnant rats were water deprived for 3 days at late gestation, and we examined fetal cardiac ultrastructure, as well as heart angiotensin (Ang) II receptor protein and mRNA, liver angiotensinogen and plasma Ang II concentrations. We also tested cardiovascular responses to i.v. Ang II in the young offspring. In utero exposure to maternal water deprivation significantly decreased fetal body and heart weight, and increased fetal plasma sodium and osmolality. Fetal liver angiotensinogen mRNA, plasma Ang I and Ang II concentrations were also increased. Although fetal AT(1a) and AT(1b) receptor mRNA and AT(1) protein were not changed, AT(2) receptor mRNA and protein levels in the heart were significantly increased following maternal dehydration. Prenatal exposure to maternal water deprivation had no effect on baseline BP; however, it significantly increased BP in response to i.v. Ang II infusion, and decreased baroreflex sensitivity in the offspring. In addition, the heart AT(2) receptor mRNA and protein were higher in the offspring exposed to prenatal dehydration. The results of this study demonstrate that prenatal dehydration affected the RAS development associated with an Ang II-increased BP in fetal origin.

Effects of water deprivation on drug pharmacokinetics: correlation between drug metabolism and hepatic CYP isozymes

Male Sprague-Dawley rats deprived of water for 72 h (a rat model of dehydration) showed no change in protein expression of the hepatic microsomal cytochrome P450 (CYP) 1A2, 2B1/2, 2C11, or 3A1/2, but an increase in protein expression (3-fold) and mRNA level (2.6-fold) of CYP2E1. Glucose feeding instead of food normalized CYP2E1 protein expression during dehydration. Here, we review how dehydration can change the pharmacokinetics of drugs reported in the literature via changing CYP isozyme levels. We also discuss how dehydration changes the pharmacokinetics of drugs that are metabolized via renal DHP-I, or are mainly excreted in the urine and bile, and form conjugates.

Pharmacokinetic interaction between DA-8159, a new erectogenic, and metformin in rats: competitive inhibition of metabolism via hepatic CYP3A1/2

BACKGROUND AND PURPOSE

Erectile dysfunction is highly prevalent in diabetic patients and PDE V inhibitors are effective and safe for the treatment of erectile dysfunction in men with diabetes. Therefore, in this study we investigated whether a pharmacokinetic interaction occurs between DA-8159 and metformin, as both drugs are metabolized via hepatic CYP3A1/2 in rats.

EXPERIMENTAL APPROACH

DA-8159 (30 mg kg(-1)) and metformin (100 mg kg(-1)), both separately and together, were administered to rats either intravenously or orally. The V (max), K (m), CL(int), apparent inhibition constants (K (i)), [I]/K (i) and concentrations of each drug in the liver and intestine were then measured.

KEY RESULTS

After i.v. administration of both drugs simultaneously, the AUC of DA-8159 and metformin was significantly greater (21.2 and 33.9% increase for DA-8159 and metformin, respectively) than that of each drug alone. After p.o. administration of the drugs, the AUC of metformin was also significantly greater (20.7% increase) in the presence of DA-8159 than in its absence. However, the AUC of DA-8159 was similar in the absence and presence of metformin.

CONCLUSIONS AND IMPLICATIONS

The significantly greater AUC of metformin and DA-8159 after i.v. administration of both drugs and of metformin after p.o. administration of both drugs is probably due to competitive inhibition for the metabolism of these drugs via hepatic CYP3A1/2. However, the similar AUCs of DA-8159 in the absence and presence of metformin, after p.o. administration, indicates that the dose of metformin used was insufficient to inhibit the hepatic and intestinal metabolism of DA-8159.