The regulation of sodium excretion by the kidneys. Part 2.

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

1 encoded moving image.

00:38:17

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 Mills begins by summing up the content of Part One, in particular, to the experiment by his colleague de Bono in which a dog had a left kidney wrapped in latex, thus reducing its function. Mills then turns to discussing the effect of the protein angiotensin on the kidneys, he explains how angiotensin produces sodium retention. Time start: 00:00:00:00 Time end: 00:04:55:00 Length: 00:04:55:00

Segment 2 Mills shows a graph detailing the results of an experiment using angiotensin on the left renal artery. The results show that although angiotensin reduces sodium excretion rapidly in the first 10 minutes, it begins to rise again after that, although not to normal levels. Thus, the kidney clearly has a way of regulating itself despite changes in body chemistry. He now shows a graph with the results of an experiment in which both angiotensin and the hormone noradrenaline were infused into the left kidney. The kidney was unable to become resistant to the effects of noradrenaline and Mills explains why the kidney can adjust to angiotensin but not to noradrenaline. Time start: 00:04:55:00 Time end: 00:10:39:00 Length: 00:05:44:00

Segment 3 Mills now turns to look at the effects of the sympathetic nerves on the vasodilation of the kidneys. He shows graphs and charts relating to an experiment on dogs. These conclude that the sympathetic nerves play an important role in the rate of sodium excretion. Time start: 00:10:39:00 Time end: 00:15:32:15 Length: 00:04:53:15

Segment 4 Mills, gathering together data accumulated so far, proposes a hypothesis, illustrated by diagrams. He says that people with autonomic dysfunction and postural hypertension excrete more sodium than normal and that there is raised kallikrein (an enzyme) in their urine. Time start: 00:15:32:15 Time end: 00:20:04:00 Length: 00:04:32:10

Segment 5 Mills continues to discuss kallikrein. He shows graphs detailing the relationship between sodium excretin and kallikrein excretion in normal subjects and in people with various degrees of renal failure. Time start: 00:20:04:00 Time end: 00:25:57:00 Length: 00:05:53:00

Segment 6 Mills now shows a graph which details how kallikrein and sodium excretion levels are changed following the consumption of water - the kallikrein secretion levels increase dramatically but not the sodium excretion. He draws the conclusion that perhaps the renal vessels resistance to angiotensin might be due to the production of kallikrein. He shows graphs which chart sodium and kallikrein excretion levels following infusion with angiotensin. Time start: 00:25:57:00 Time end: 00:31:09:00 Length: 00:05:12:00

Segment 7 Mills moves on to talk about the oncotic pressure (the process by which water is pulled into the blood stream) in the plasma surrounding the tubules of the kidney. He shows the results of an experiment by Windhanger on the kidney's proximal tubule, then reminds us of the experiment with the dog with the wrapped left kidney. Mills concludes by saying that "much research must be done before we understand the complicated mechanism by which the kidney excretes both sodium and water." Time start: 00:31:09:00 Time end: 00:38:17:19 Length: 00:07:09:06