Cell Volume Regulation, Ions, and Apoptosis

Abstract

It is generally accepted that all cells have the ability to undergo an internally controlled cell suicide process known as apoptosis, or programmed cell death, in response to a given stimulus or environmental agent³⁹. The apoptotic process efficiently removes or eliminates a population of unwanted cells from the body at a given time in the absence of an inflammatory response. This mode of cell death has been observed during development^25,37,40, in the immune system², and in the progression of both AIDS^21,33,34 and cancer^24,35,38. Apoptosis is characterized by a distinct set of morphological and biochemical features including cell shrinkage, nuclear condensation, proteolysis, internucleosomal DNA cleavage, and apoptotic body formation²⁷. Over the past 20 years, much attention has focused on the biochemical aspects of apoptosis, including the intracellular signals leading to cell death, the enzymes involved in both protein and DNA degradation, and the role several apoptotic modulating genes play to control or inhibit cell death¹². However, of all the characteristics which define this mode of cell death, the observation that the cells shrink or lose volume during apoptosis has remained relatively unexplored.