Hi, how’s the new meal plan working with the rice swap and increased milk and coconut water?
Active Transport vs. Pumps. Is Gilbert Ling's Theory on Active Transport incompatible with the use of so-called pumps used heavily to rationalize the transport of electrolytes such as sodium and potassium from the cell to the extracellular milieu ?
Gilbert Ling's theory of active transport is indeed fundamentally incompatible with the concept of "pumps" as they are conventionally used to explain the movement of electrolytes like sodium and potassium across cell membranes. Ling's work challenges the very foundation of the membrane pump hypothesis, which posits that specific molecular pumps actively transport ions against their concentration gradients using cellular energy, typically ATP.
Ling argued that the energy requirements for such pumps to maintain ionic gradients are far beyond what the cell can realistically produce. He demonstrated through biophysical calculations and experiments that the selective distribution of ions is better explained by the physical and chemical properties of the cell's internal environment, particularly the interaction of ions with cellular proteins and water. For example, the affinity of proteins for potassium over sodium, influenced by their charge and structural configuration, can account for the observed ionic distributions without invoking energy-intensive pumps 1248.
Furthermore, Ling's association-induction hypothesis emphasizes the role of the cytoplasm's structural organization and the inductive effects of molecules like ATP in creating the conditions for ion selectivity. This view aligns with evidence showing that the cell's bulk phase, rather than its membrane, regulates water and solute distribution. The membrane pump model, by contrast, relies on a mechanistic and energetically implausible explanation that fails to account for the coherent behavior of ions and water in living cells 468.
In essence, Ling's theory replaces the idea of pumps with a more holistic understanding of cellular physiology, where the cell's energy is primarily devoted to maintaining its structural integrity and metabolic processes, rather than driving hypothetical pumps that would require an unrealistic amount of energy 68. This perspective not only challenges the pump-centric view but also opens the door to a more integrated and energy-efficient understanding of cellular function.