Please help me answer the questions below in reference to the reading below: QUE

Question

Please help me answer the questions below in reference to the reading below:

QUESTION 1: WHY did ketonemia occur in the experiment, in your opinion?

QUESTION 2: WHY do you think that the ammonia content of both urine and renal venous blood fell markedly so that ammoniogenesis was depressed by 60% or more within 60 minutes after the onset of infusion?

Infusion of ketone bodies to ammonium chloride-loaded acidotic dogs was found to induce significant reduction in urin#ary excretion of ammonia. This effect could not be attributed to urinary pH variations. (1) Total ammonia production by the left kidney was measured in 25 animals infused during 90 min with the sodium salt of D,L--hydroxybutyric acid adjusted to pH 6.0 or 4.2. Ketonemia averaged 4.5 mM/liter. (2) . In all experiments the ammonia content of both urine and renal venous blood fell markedly so that ammoniogenesis was depressed by 60% or more within 60 min after the onset of infusion. (3). Administration of equimolar quantities of sodium acetoacetate adjusted to pH 6.0 resulted in a 50% decrease in renal ammonia production. (4) Infusion of ketone bodies adjusted to pH 6.0 is usually accompanied by a small increase in extracellular bicarbonate (3.7 mM/liter). However infusion of D,L-sodium lactate or sodium bicarbonate in amounts sufficient to induce a similar rise in plasma bicarbonate resulted in only a slight decrement in ammonia production (15%). The continuous infusion of 5% mannitol alone during 90-150 min failed to influence renal ammoniogenesis. (5) Infusion of pure sodium-free -hydroxybutyric acid prepared by ion exchange (pH 2.2) resulted in a 50% decrease in renal ammoniogenesis in spite of the fact that both urinary pH and plasma bicarbonate fell significantly. (6) During all experiments where ketones were infused, the renal extraction of glutamine became negligible as the renal glutamine arteriovenous difference was abolished. Renal hemodynamics did not vary significantly. Infusion of -hydroxybutyrate into the left renal artery resulted in a rapid decrease in ammoniogenesis by the perfused kidney. (7) The present study indicates that ketone bodies exert their inhibitory influence within the renal tubular cell. Since their effect is independent of urinary or systemic acid-base changes, it is suggested that they depress renal ammoniogenesis by preventing the transformation of glutamine and glutamate into -ketoglutarate in the mitochondria of the renal tubular cell. (8)

Explanation / Answer

QUESTION 1 ANSWER --- In all experiments the ammonia content of both urine and renal venous blood fell markedly so thatammoniogenesis was depressed by 60% or more within 60 min after the onset of infusion. Infusion of ketone bodies to ammonium chloride-loaded acidotic dogs was found to induce significant reduction in urinary excretion of ammonia. This effect could not be attributed to urinary pH variations. Total ammonia production by the left kidney was measured in 25 animals infused during 90 min with the sodium salt of D,L-beta-hydroxybutyric acid adjusted to pH 6.0 or 4.2. Ketonemia averaged 4.5 mM/liter.We also stress that the renal contribution to acid-base balance must occur without ..... must be such that it does not lead to the formation of precipitates in the urine.

QUESTION 2 -- The integrity of the renal concentrating mechanism is maintained by the anatomical and functional arrangements of the renal transport mechanisms for solute (sodium, potassium, urea, etc) and water and by the function of the regulatory hormone for renal concentration, vasopressin.Urine concentrating ability is reduced during normal aging in people and rats. The abundance of many of the key transport proteins that contribute to urine concentrating ability is reduced in the kidney medulla of aged rats.The antidiuretic hormone arginine vasopressin is a systemic effector in urinary concentration. However, increasing evidence suggests that other locally produced factors may also play an important role in the regulation of water reabsorption in renal collecting ducts.  the effect of the volume of fluid ingested on urine concentrating ability during prolonged heavy exercise in a hot environment at low levels of dehydration. Seven healthy males performed 105 min of intermittent cycle exercise at 70% maximum oxygen uptake (32°C, 60% relative humidity) while receiving no fluid ingestion (NF), voluntary fluid ingestion (VF), partial fluid ingestion equivalent to one-half of body mass loss (PF).

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