News in Physiological Sciences

The regulation of body fluid volumes has long been a puzzle. For example, what factors are involved in correcting the volume expansion during and following the intravenous infusion \ of isotonic saline? In other words, how is the blood volume maintained and the “milieu interieur” kept within narrow limits? Several factors such as aldosterone, the antidiuretic hormone arginine vasopressin, and others play a role in the regulation of blood volume. The low pressure elements of the heart, the atria, have more recently been implicated as being in the most suitable area to “sense the fullness of the blood stream.” Exciting recent discoveries clarify the major endocrine connection between heart and kidney. Many cells in heart atria contain secretory granules that release their contents in response to stretch, whether caused by increased perfusion pressure or expanded blood volume. The work done on the granular cells since early 1970 by three major groups, Cantin in Montreal, Bencosme in Kingston, Canada, and Hatt in Paris, has led to the demonstration by de