MP866A BRIEF HISTORY OF THE STUDY OF DIFFUSION AND OSMOSIS IN THE CONTEXT OF DIALYSIS

Abstract

INTRODUCTION AND AIMS: Currently around 3 million people are treated with haemodialysis. Haemodialysis has had a long journey from the first attempts with a membrane from cellulose tubing for sausage manufacture up to the high technology membranes with excellent biocompatibility and apart from that, with high sorptive capacity. But what happened before that? How did the theoretical prerequisites come to be to make this possible?METHODS: Haemodialysis is based on diffusion - the movement of molecules across the semi-permeable membrane along the concentration gradient. The first described aspect of diffusion is osmosis - the process of diffusion across the semi-permeable membrane of the solvent towards the more concentrated solution. This phenomenon was first observed by the French abbot Jean-Antoine Nollet in 1748. However, it was the doctor René Joachim Henri Dutrochet who first described it in detail and introduced the term “osmosis” 80 years later. When studying the generation and movement of sap in botanic tissues, he described “endosmosis”- the rapid transfer of solvent water in tissues, and exosmosis - the slower transfer of solute in the opposite direction. During trials, the scientist found the same effects were produced in animal tissues. Dutrochet is also known for the invention of the first osmometer. It is interesting that the scientist initially considered osmosis to be the manifestation of the “vital force”. He tried replacing the biological membrane with a porous clay vessel, expecting this experiment to fail, however he still observed the osmotic movement of liquid. Thus, Dutrochet showed that osmosis is purely a physical phenomenon, and he “forever united physics with physiology”.