Abstract
Summary
1. Three well trained standardized dogs were given excess sodium chloride in the diet in amounts approximating 2.5 g per kg weight for 205, 56 and 154 days respectively. The first effect was a marked increase in the daily variations in blood pressure and a small but significant elevation of the systolic pressure. In only one dog was the diastolic pressure elevated. As excess salt ingestion was continued there was evidence of increasing adaptation characterized by a drop in the previously elevated systolic pressure. Adaptation finally became so highly developed that when the salt stress was increased by giving 2% saline solution as the sole source of drinking water, 2 dogs showed no additional elevation in systolic pressure while one showed a small but significant elevation. 2. After adaptation to salt was complete, a second stress caused elevation of both systolic and diastolic pressure but continuation of the second stress led to adaptation. 3. The sudden withdrawal of excess salt after administration for 254, 105 and 189 days, respectively, was quickly followed by a marked and highly significant fall in both systolic and diastolic blood pressure, which persisted for at least 3 weeks. A possible cause for this drop in pressure is discussed.
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