Question

Action of Ouabain on Kidney Tissue Ouabain specifieally inhibits the \(\mathrm{Na}^{+} \mathrm{K}^{+}\)ATPase activity of animal tissues but is not known to inhibit any other enzyme. When ouabain is added to thin slices of living kidney tissue, it inhibits axygen consumption by 6696 . Why? What does this observation tell us about the use of respiratory energy by kidney tissue?

Short answer

Ouabain decreases oxygen consumption by inhibiting Na+/K+ ATPase, indicating kidney tissue heavily uses energy for ion transport.

Step-by-step solution

Understand the role of Na+/K+ ATPase

The enzyme Na+/K+ ATPase is responsible for maintaining the gradient of sodium (Na+) and potassium (K+) ions across the cell membrane by actively transporting Na+ out and K+ into the cell. It does this using energy derived from ATP, a key cellular energy currency.

Relate Na+/K+ ATPase function to oxygen consumption

The Na+/K+ ATPase activity is a significant process, consuming large amounts of ATP. For ATP production, cells require oxygen as part of the aerobic respiration process. Inhibiting Na+/K+ ATPase reduces ATP demand, which in turn decreases the cell's need to consume oxygen to produce ATP.

Connect ouabain's inhibition impact with kidney tissue

As ouabain inhibits Na+/K+ ATPase, it diminishes ATP consumption, and consequently, less oxygen is needed to produce ATP. Therefore, the reduced oxygen consumption observed when kidney tissue slices are exposed to ouabain highlights the enzyme's substantial energy demand in kidney function.

Key concepts

Kidney Tissue Physiology

The kidney is a complex organ that plays a vital role in maintaining homeostasis in the body. Its primary function is to filter blood, remove waste, regulate electrolyte balance, and manage blood pressure. Within the kidney, millions of tiny filtering units called nephrons ensure the organ performs these tasks efficiently.
Each nephron comprises a glomerulus and a tubule, performing different stages of filtration and reabsorption. The correct function of these structures is crucial for maintaining the body's internal balance. One core physiological aspect of kidney function is its reliance on active transport systems, such as the Na+/K+ ATPase pump.

• The Na+/K+ ATPase maintains ion gradients by moving sodium ions out of and potassium ions into the cells.
• This ionic movement is essential for various renal processes, including maintaining a proper osmotic balance and facilitating the reabsorption of essential nutrients and water.

Any disruption in these processes, such as through the action of inhibitors like ouabain, can significantly impact kidney tissue functionality.

Oxygen Consumption

Oxygen consumption within kidney tissues is closely linked to their metabolic activities. Kidneys are highly energy-demanding organs due to their critical role in filtering and concentrating urine.
Aerobic respiration, a primary method of energy production within cells, heavily depends on oxygen. This process fuels ATP production, crucial for numerous cellular activities, including active transport mechanisms like the Na+/K+ ATPase pump.

• The inhibition of Na+/K+ ATPase, as observed with ouabain, results in lower ATP requirements.
• With less need for ATP, cells reduce their oxygen consumption, showcasing a direct link between enzyme activity and respiratory energy demands.

This highlights how integral the Na+/K+ ATPase process is to kidney tissue physiology and its influence on overall energy usage.

Role of ATP in Cellular Function

Adenosine triphosphate (ATP) is the primary energy currency of the cell. It provides the energy required for numerous physiological processes, making it vital for cellular functions. Na+/K+ ATPase is one of the major consumers of ATP in cells, especially in energy-intensive organs like the kidney.

• ATP facilitates the active transport mechanisms that help maintain ion gradients across the cell membrane.
• These gradients are essential for nerve impulse transmission, muscle contraction, and maintaining fluid and electrolyte balance.

Inhibiting the Na+/K+ ATPase affects these gradients, as seen with ouabain's action, which ultimately impacts cellular and organ-level functionality. Understanding the central role of ATP in sustaining cellular activities helps explain why any alteration in its availability would affect essential biological functions.