A student laboratory exercise illustrating active transport across the small intestine

¹ Department of Physiology, Harvard Medical School, Boston, Massachusetts

A 7-year experience with student laboratory exercises dealing with intestinal transport in vitro is described. A single experiment which has evolved from trial and error in the student laboratory is given in detail. Everted sacs of small intestine from the golden hamster are incubated in flasks containing bicarbonate-saline with 10 mm glucose and 2 mm d- or l-tyrosine. Glucose and l-tyrosine are transported across the intestinal wall against concentration gradients; d-tyrosine is not, illustrating the stereospecificity of the amino acid transport system. A second experiment which illustrates the stimulation of vitamin B₁₂ absorption by gastric intrinsic factor is briefly recorded. The student interest aroused and the high degree of satisfactory results make such experiments useful additions to the repertoire of student laboratory exercises in physiology.

Submitted on November 12, 1964