ABSTRACT
I. Introduction 145
II. Membranes, Rafts, and Lung Surfactant 148
III. Chain Dancing 150
IV. Nanotubes Revisited 152
V. Physiological Correlates 154
VI. Supercool Surfactant 156
VII. The Cholesterol Mystery 159
VIII. Heavy Breathing: Critical Behavior Disrupted 162
IX. The Future 165
Acknowledgments 166
References 166
I. Introduction
Lung surfactant (LS) was perhaps discovered a few centuries ago by a seafarer,
Fredric Marten (1671), who described LS as, “When the whales blow up water,
they fling out with some fattish substance that floats up on the sea like sperm and
this fat the Mallemucks (sea-gulls?) devour greedily” (1). Beyond being an item
of bird feed, today we know that this material is found in all mammalian lungs
(and some other parts of the body), originates in the pulmonary type-II cells,
and its lack thereof or dysfunction causes “heavy” or distressed breathing
(2,3). We also comprehend that the LS is complex, behaves like an extracellular
membrane, although unusual in composition compared to mammalian cell mem-
branes (3,4). The physical property of the material has been studied using various
physico-chemical methodologies. The simplest of them all is Irving Langmuir’s
“phenomenon in (Alice’s!) Flatland” (5,6). These are the studies on monolayers
and some complex liquid crystalline anisotropic arrangement of molecules
in soaps (7). Surfactant is defined by DeGennes in his Nobel Lecture (1991),
“Surfactants allow us to protect a water surface and to generate beautiful soap
bubbles which delight our children” (7).
