Eutrophication and Phosphate Detergents

concept argue that from 9 to 23 percent of the cellular metabolic energy is required for the operation of the sodium pump (3). The question is, then, whether the cell can provide the energy necessary to pump potassium, calcium, magnesium, sugars, and amino acids if it takes 10 percent of the energy to run only one pump? Recently, some alternative hypotheses, often referred to, in general, as the minority view of the cell, have been proposed. Among them the most systematic one is the association-induction hypothesis proposed by Ling. According to this hypothesis, the cell is considered a highly complex system, wherein many of the biological processes are controlled by interaction of ion, water, and macromolecule. The intracellular concentration of any ion will be determined by its association energy (attraction) to macromolecular fixed charged sites and the solvent properties of the cellular water. For example, potassium is preferentially associated with the fixed charges on proteins within the cell, and the sodium concentration is low, primarily because the cellular water is more structured than ordinary water and therefore less sodium is dissolved in it. Another point of the associationinduction hypothesis is that the surface of most cells possesses a net negative charge. Therefore, the cellular potential is a phase boundary potential and not a membrane potential. The postulation of a net negative charge at the surface leads to the prediction that permeation of certain ions into the cell are surface limited (that is, they interact with the fixed negative charges on the surface) and others are bulk phase limited (that is, the major resistance to movement into the cell is the structured water and fixed sites within the cell and not the membrane). That diffusion into smooth and skeletal muscle is surface limited for potassium and bulk phase limited for sodium has been borne out experimentally (4). As a proponent of the minority view, I argue that the physical state of the ions and water within the cell are all important and intimately involved in the mechanisms that regulate the internal environment. Certainly the minority view is not proved; however, a large body of evidence has accumulated in support of this view (5). Much of the recent evidence questions the validity of the fundamental assumptions