Diuretics That Block Sodium Channels in the Collecting Tubules Decrease Sodium Reabsorption Amiloride and triamterene also inhibit sodium reabsorption and potassium secretion
in the collecting tubules, similar to the effects of spironolactone. However, at the cellular level, these
drugs act directly to block the entry of sodium into the sodium channels of the luminal membraneof
the collecting tubule epithelial cells.
Acute Renal Failure The causes of acute renal failure can be divided into three main
categories:
1. Acute renal failure resulting from decreased bloodsupply to the kidneys; this condition is
often referred to as prerenal acute renal failure to reflect the fact that the abnormality occurs as a
result of an abnormality originating outside the kidneys. For example, prerenal acute renal failure can
be a consequence of heart failure with reduced cardiac output and low blood pressure or conditions
associated with diminished blood volume and low blood pressure, such as severe hemorrhage.
2. Intrarenal acute renal failure resulting from abnormalities within the kidney itself, including those
that affect the blood vessels, glomeruli, or tubules.
3. Postrenal acute renal failure, resulting from
obstruction of the urinary collecting system anywh re fromthe calyces to the outflow from the bladder.
