**Core Concept:** Acute Metabolic Acidosis: A condition characterized by a rapid increase in the production of hydrogen ions (H+) leading to a decrease in pH of the blood plasma. It can be caused by various factors like respiratory failure, lactic acidosis, or gluconeogenesis abnormalities. Acidosis alters the cellular and tubular ion concentrations.

**Why the Correct Answer is Right:** Acute Metabolic Acidosis leads to an increase in intracellular K+ concentration as cells attempt to counteract the acidic environment by importing more potassium (K+) ions. Additionally, the acidosis causes renal tubules to secrete more potassium (K+) ions to eliminate the excess H+ ions from the body, primarily through the renal collecting ducts.

**Why Each Wrong Option is Incorrect:**

A. Incorrect because it does not address the effect of acidosis on intracellular K+ concentration or K+ secretion by renal tubules.
B. Incorrect because it only addresses the effect on intracellular K+ concentration and does not mention the renal tubules' role in K+ secretion.
C. Incorrect because it only addresses the effect on intracellular K+ concentration without mentioning the renal tubules' role in K+ secretion.
D. Incorrect because it only addresses the effect on intracellular K+ concentration without mentioning the renal tubules' role in K+ secretion.

**Clinical Pearl:** Understanding the effects of acidosis on intracellular K+ concentration and renal tubules is crucial for diagnosing and managing patients with acute acidosis. Acidosis can lead to hyperkalemia (elevated K+ levels) if not appropriately managed, which can lead to cardiac arrhythmias and life-threatening complications. On the other hand, it can also lead to hypokalemia (low K+ levels) when acidosis is severe and not adequately treated, which can cause muscle weakness, paralysis, and respiratory failure.

**Correct Answer:** D. Acidosis leads to an increase in intracellular K+ concentration and K+ secretion by renal collecting ducts in response to the acidosis-induced hyperpolarization of the cell membrane. This helps to decrease the reabsorption of K+ ions and increase K+ secretion, ultimately leading to hypokalemia, which is a common complication of uncontrolled acidosis.