The regulation of sodium excretion by the kidneys. Part 1.

London : University of London Audio-Visual Centre, 1973.

1 encoded moving image (40.06 min.) : sound, color.

00:40:06

University of London

Some restrictions.

CC-BY-NC

In English

Presented by Professor Ivor Mills, Addenbrooke's Hospital, Cambridge. Introduced by Dr Ian Gilliland. Produced by Peter Bowen. Made for British Postgraduate Medical Federation. Made by University of London Audio-Visual Centre.

This video is one of around 310 titles, originally broadcast on Channel 7 of the ILEA closed-circuit television network, given to Wellcome Trust from the University of London Audio-Visual Centre shortly after it closed in the late 1980s. Although some of these programmes might now seem rather out-dated, they probably represent the largest and most diversified body of medical video produced in any British university at this time, and give a comprehensive and fascinating view of the state of medical and surgical research and practice in the 1970s and 1980s, thus constituting a contemporary medical-historical archive of great interest. The lectures mostly take place in a small and intimate studio setting and are often face-to-face. The lecturers use a wide variety of resources to illustrate their points, including film clips, slides, graphs, animated diagrams, charts and tables as well as 3-dimensional models and display boards with movable pieces. Some of the lecturers are telegenic while some are clearly less comfortable about being recorded; all are experts in their field and show great enthusiasm to share both the latest research and the historical context of their specialist areas.

Segment 1 Dr Ian Gilliland introduces Professor Ivor Mills, giving a potted history of his medical background. Mills then speaks to camera and explains how complex the subject of regulated sodium excretion is. He recounts research from the 1950s, in particular the role of the hormone aldosterone in the regulation of sodium excretion. He shows a diagram of a kidney tubule, pointing out which parts of it are most concerned with sodium excretion and reabsorption. Time start: 00:00:00:00 Time end: 00:05:19:00 Length: 00:05:19:00

Segment 2 Mills shows a diagram detailing an experiment on a dog's kidneys. The experiment aimed to show that aldosterone, in fact, was not a major factor in the regulation of sodium excretion. The experiment also shows that when the function of one of the dog's kidneys was constricted, sodium excretion still occurred. A graph is shown giving the results of the experiment. Mills then focuses on a second experiment in which two dogs were joined together by the femoral arteries and veins. He shows a diagram to illustrate the experiment. Saline was injected into one and allowed to flow into the other; the urine flow and sodium excretion was then measured; the dog who received the saline injection showed the greatest increase in sodium excretion. Time start: 00:05:19:00 Time end: 00:12:27:00 Length: 00:07:08:00

Segment 3 Mills continues to refer to the experiment with the two dogs joined together. He shows diagrams and explains how inulin can be injected into one of the tubules. Then inulin blood plasma levels and sodium excretion are measured and compared in each dog. Time start: 00:12:27:00 Time end: 00:16:46:00 Length: :00:04:19:00

Segment 4 Mills focuses specifically on the tubules themselves, using detailed diagrams. He proves that the geometry of the tubule itself is not responsible for levels of sodium excretion, as has been previously believed, but that there is a further more important factor in the process. Time start: 00:16:46:00 Time end: 00:21:17:00 Length: 00:04:31:00

Segment 5 An experiment from de Wardener is shown in which blood is taken from an anaesthetised dog and pumped through a bottle containing albumin and saline. The blood was gradually diluted and levels of sodium excretion measured. The results showed that increases in blood volume produced increases in sodium excretion. Time start: 00:21:17:00 Time end: 00:24:45:00 Length: 00:03:28:00

Segment 6 Mills goes on to talk about experiments on the renal tree. He refers to an experiment in which the vasodilator Bradykinin is injected into the renal tree. Results showed that the Bradykinin increased sodium excretion from the injected kidney. Mills then shows a chart detailing all the various methods of causing dilatation in the renal tree. This is followed by a diagram showing the process of sodium excretion by a single kidney. Time start: 00:24:45:00 Time end: 00:31:30:20 Length: 00:06:45:20

Segment 7 Mills explains that the kidney on its own can control sodium excretion without the intervention of any other organ providing hormones although these other organs do help to regulate the quantities of sodium excretion. He then refers to an experiment on dogs, by his colleague de Bono, in which the left kidney was wrapped in latex and saline was infused at a rapid rate. The right kidney excreted sodium normally while the left was severely impaired. Time start: 00:31:30:20 Time end: 00:36:30:15 Length: 00:05:00:19

Segment 8 Mills continues to discuss the experiment by de Bono. Frusemide (a diuretic medication) is given intravenously and the wrapped left kidney shows an increase in sodium excretion. Mills concludes the lecture and discusses, briefly, the subjects to be discussed in part two. Time start: 00:36:30:15 Time end: 00:40:06:18 Length: 00:03:36:03