Daily Rhythms of Renal Excretion in Arctic‐dwelling Indians and Eskimos

Abstract

The daily rhythms of renal excretion of indigenous arctic subjects were recorded under natural conditions during the continuous midsummer daylight (Indians and Eskimos) and in the continuous darkness of midwinter (Indians only). The excretory patterns for water, potassium, sodium and chloride have been compared with those of a group of British control subjects, recorded when they were newly introduced into a summer arctic environment in adult life. In general, the excretory patterns of the arctic subjects contain a high proportion of abnormalities, such that the averaged patterns for the indigenous groups are less well defined than are those for the control group of subjects from a temperate zone. The loss of definition of the rhythms is most marked in the Eskimo subjects, where differences between day and night excretory rates have virtually disappeared. Mathematical analysis of the individual results shows that the relative amplitude of the rhythm of potassium excretion decreases from British controls → summer Indians → winter Indians → summer Eskimos. The differences between control subjects and all indigenous subjects and between Indians and Eskimos are significant, and cannot be accounted for by variations in age, activity pattern or diet. It is suggested that the normal daily alternation of light and darkness in the environment is important not only for the day‐to‐day maintenance of renal diurnal rhythms but also for the initiation and full expression of these rhythms in the early life of the human subject.

Rhythmicity of chromophore turnover of visual pigment in the Antarctic amphipod Orchomene plebs (Crustacea; Amphipoda)

“…No circadian pattern of melatonin or cortisol secretion in Weddell seals was apparent under natural, Antarctic summer conditions (Barrell and Montgomery 1989). Even Eskimos are reported not to show the regular 24-hour periodicity of urine production and potassium excretion (Lobban 1967) and in European volunteers of Svalbard (Spitzbergen) synchronization of the circadian system did not take place supposedly because of the weakness of the Zeitgeber (Johnson et al 1979). On the evidence of these publications neither the sun nor cyclic fluctuations in the vertical component intensity of the earth's magnetic field, as suggested by Bliss and Heppner (1976) must have been strong or clear enough clues to set up and maintain circadian rhythms.…”

Problems related to shift work. A field study of Swedish railroad workers with irregular work hours.

“…There 20 Ofo of the persons had long-standing peptic disorders, and 10 Ofo had been away from work for this reason. We found peptic ulcers ,in 13 Ofo 'and gastritis in [26][27][28][29] 11/0, respectively. 'I1his frequency its higher than what has been found for other groups, e.g., dock workers (30), but it is in accord with the findings of Bjerner et al (6), who found that traveling railroad personnel had more peptic ulcers ,than Swedes in general.…”

“…In animals ,the change from light to darkness and fmm darkness to light is a very strong synchronizer (19) or "Zettgeber" (4). In man, on Ithe other hand, sociarl rellatoons !Seem <to be stiN more impontlant (6,27). A great number of social complication!S wel'e .reported in shift workers when the family and community followed a daytime pattern (32).…”

Urinary cycles

“…The daily rhythms of renal excretion of indigenous arctic Indians and Eskimos have been described in detail elsewhere (Lobban, 1967). Briefly, abnormalities occurred relatively frequently in the excretory rhythms of these arctic-dwellers, such that although in the averaged patterns for indigenous arctic communities temporal relationships similar to those of control (temperate zone) groups were maintained, the peak to trough range and relative amplitude of the rhythms were reduced.…”