Absorption and metabolism of benzoic acid in growing pigs.

Dietary benzoic acid (BA) supplementation causes a pronounced reduction in urinary pH but only small changes in blood pH. The present study aimed to investigate the portal absorption profile, hepatic metabolism of BA, and renal excretion of hippuric acid (HA) underlying the relatively small impact of BA on systemic acid-base status. Eight growing pigs (BW = 63 +/- 1 kg at sampling) fitted with permanent indwelling catheters in the abdominal aorta, hepatic portal vein, hepatic vein, and mesenteric vein were allocated to 4 sampling blocks and randomly assigned to control (CON; nonsupplemented diet) or BA supplementation (B; control diet + 1% BA top-dressed).

Normotensive sodium loading in conscious dogs: regulation of renin secretion during beta-receptor blockade.

Renin secretion is regulated in part by renal nerves operating through beta1-receptors of the renal juxtaglomerular cells. Slow sodium loading may decrease plasma renin concentration (PRC) and cause natriuresis at constant mean arterial blood pressure (MAP) and glomerular filtration rate (GFR). We hypothesized that in this setting, renin secretion and renin-dependent sodium excretion are controlled by via the renal nerves and therefore are eliminated or reduced by blocking the action of norepinephrine on the juxtaglomerular cells with the beta1-receptor antagonist metoprolol.

Systemic effects of angiotensin III in conscious dogs during acute double blockade of the renin-angiotensin-aldosterone-system.

Aims: The study was designed to determine (i) whether the effects of angiotensin III (AngIII) are similar to those of angiotensin II (AngII) at identical plasma concentrations and (ii) whether AngIII operates solely through AT1- receptors.

Methods: Angiotensin II (3 pmol kg(-1) min(-1)-3.1 ng kg(-1) min(-1)) or AngIII (15 pmol kg(-1) min(-1)-14 ng kg(-1) min(-1)) was infused i.

Effects of sodium intake on plasma potassium and renin angiotensin aldosterone system in conscious dogs.

Aims: The operating range of the renin-angiotensin-aldosterone system is ill-defined. This study quantifies renin-angiotensin-aldosterone system activity as a function of sodium intake.

Methods: Renin-angiotensin-aldosterone system variables were measured daily after a sudden reduction in sodium intake (3.

Volume natriuresis vs. pressure natriuresis.

Body fluid regulation depends on regulation of renal excretion. This includes a fast vasopressin-mediated water-retaining mechanism, and slower, complex sodium-retaining systems dominated by the renin-angiotensin aldosterone cascade. The sensory mechanisms of sodium control are not identified; effectors may include renal arterial pressure, renal reflexes, extrarenal hormones and other regulatory factors.

Energy intake and milk production in mink (Mustela vison)--effect of litter size.

Energy intake and milk production were measured in 12 mink dams raising litters of 3, 6 and 9 kits one to four weeks post partum by means of balance experiments and measurements of milk intake of the kits by the water isotope dilution technique. The dams were fed ad libitum on a conventional wet mink diet (DM: 323 g/kg; CP: 173 g/kg; ME: 4.4 MJ/kg).

High versus low protein diets to mink--postprandial plasma urea and creatinine response, osmotic load and pattern of nitrogen and electrolyte excretion.

Nitrogen balance, pattern of excretion of nitrogenous end-products, endogenous urinary N excretion, postprandial plasma urea and creatinine, osmotic load, urinary electrolyte excretion and water intake/output relationships were studied in 12 adult female mink fed a high protein diet (HP; n = 6) providing about 155 g protein/kg or a low protein diet (LP; n = 6) providing about 95 g protein/kg. Two balance periods of each 3 d were used and diets were fed raw or cooked. After the last balance period followed a 48 h fasting period.

Preservation of active incretin hormones by inhibition of dipeptidyl peptidase IV suppresses meal-induced incretin secretion in dogs.

The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are degraded by dipeptidyl peptidase IV (DPP IV), thereby losing insulinotropic activity. DPP IV inhibition reduces exogenous GLP-1 degradation, but the extent of endogenous incretin protection has not been fully assessed, largely because suitable assays which distinguish between intact and degraded peptides have been unavailable. Using newly developed assays for intact GLP-1 and GIP, the effect of DPP IV inhibition on incretin hormone metabolism was examined.

Milk intake in blue fox (Alopex lagopus) and silver fox (Vulpes vulpes) cubs in the early suckling period.

Milk intake of fox cubs (2-16 days of age; body weight, 96-649 g) in ten blue fox litters and ten silver fox litters were measured by the water isotope dilution (WID) technique following a single intraperitoneal injection of tritiated water (3HHO). Litter size varied from four to 14 in blue foxes and from three to eight in silver foxes. Silver fox cubs had higher birth weights than blue foxes.

LH release in mink (Mustela vison). Pattern of the LH surge and effect of metabolic status.

The mink is a seasonal breeder with induced ovulation and delayed implantation. Reproductive processes are strongly influenced by energy supply and body condition. Items for which there is paucity or complete lack of data were the main objectives of this study: the temporal relationship between copulation and the pre-ovulatory LH surge and the influence of energy supply on LH release.

Milk intake of suckling kittens remains relatively constant from one to four weeks of age.

The daily milk intake of 14 domestic short-haired kittens (Felis catus) from five litters was estimated during wk 1-4 postpartum using the isotope dilution technique. Kittens received a single intraperitoneal injection of tritiated water, and blood samples were obtained from the jugular vein for radioactivity measurements at 2 and 96 h after injection. One kitten in each litter was used as a control to allow calculation of recycling of tritiated water.

Daily milk intake and body water turnover in suckling mink (Mustela vison) kits.

Daily (24 h) milk intake and body water turnover were measured in eight litters of suckling mink (Mustela vison) kits (6-9 kits litter-1) during weeks 1-4 post partum using the tritiated water (3HHO) dilution technique. The biological half-life of body water turnover in the mink kits increased linearly from 0.9 days in week 1 (3-5 days post partum) to 1.

Nitrogen balance in adult female mink (Mustela vision) in response to normal feeding and short-term fasting.

Ten adult female mink (Mustela vison) were studied in a 7 d balance experiment consisting of a 2 d pre-surgery feeding period, followed by surgery, 1 d of recovery 4 d of ad libitum feeding, and a 2 d fasting period. In this experiment (Expt A) the animals had osmotic pumps implanted for continuous release of radioactively-labelled p-aminohippuric acid (p-aminobenzoyl-2-[3H]glycine; [3H]PAH; n 10) and 14C-labelled inulin ([14C]IN; n 5). Repeated 24 h collections of urine, corrected to 100% [3H]PAH or [14C]IN recovery, were used for accurate determination of N balances, 24 h urinary excretion of urea, creatinine, and total N, and calculation of mean 24 h renal clearance rates for endogenous creatinine and inulin.

Effects of feeding and short-term fasting on water and electrolyte turnover in female mink (Mustela vison).

Daily (24 h) rates of water and electrolyte turnover were measured in a conventional balance study in ten adult female pastel mink (Mustela vison) given free access to a standard mink feed for a 1-week conditioning period, followed by a 4 d experimental period and a 2 d fasting period. Drinking water was available throughout. In addition, the completeness of urine collection and the fraction of urine collected with the faeces were determined using a new experimental technique based on 24 h recoveries of specific urinary markers such as tritiated p-aminohippuric acid ([3H]PAH) or 14C-labelled inulin ([14C]IN) continuously delivered by small Alzet osmotic pumps implanted intraperitoneally.

Failure of loop diuretics to induce nursing sickness in mink at weaning.

Nursing sickness in mink is thought to be precipitated by inadequate salt intake, whether this is due to inadequate salt levels in the diet or inadequate total dietary intake. To test this hypothesis, lactating females raising large litters were given 2 daily intramuscular injections of the loop diuretic furosemide (Lasix, 4 + 4 mg/kg/day) for 2.5 d during the normal weaning period 6 wk after parturition or served as untreated controls.

Incidence of nursing sickness and biochemical observations in lactating mink with and without dietary salt supplementation.

The impact of dietary sodium on the incidence of nursing sickness in mink dams and on the average litter biomass of 28 and 42 day old kits was studied. One group (n = 115 including 12 barren females) was given a standard feed mixture with a natural content of 0.53 g NaCl/MJ and another group (n = 115 including 8 barren females) was given the same feed mixture supplemented with NaCl to a final content of 1.

Assessment of the accuracy of quantitative urine collection in mink (Mustela vison) using osmotic pumps for continuous release of p-amino-hippuric acid and inulin.

A method is described to assess the accuracy of quantitative collection of urine in small experimental animals using implanted Alzet osmotic pumps for continuous release of specific urinary markers. The nominal pumping rate (10.00 +/- 0.

Acid-base status and cardiovascular function in mink (Mustela vison) anaesthetized with ketamine/midazolam.

Heart rate, arterial blood pressure and blood acid-base status were determined in 18 adult female mink (mean (+/- SEM) body weight 1052 +/- 34 g) during long-term anaesthesia with either controlled ventilation (n=12) or spontaneous respiration (n=6). Surgical anaesthesia was induced by intramuscular injection of ketamine hydrochloride (Ketaminol Vet, 40.0 +/- 1.