Effects of insulin on renal haemodynamics and the proximal and distal tubular sodium handling in healthy subjects.
Level 3 - non-randomized controlled study
Small non-randomized within-subject experimental physiological study
PubMed 1473613 · doi:10.1007/BF02221679
What was done
Ten healthy males underwent euglycemic insulin clamp infusions on separate days to achieve two distinct levels of hyperinsulinemia (41 ± 3 mU/l and 90 ± 7 mU/l). Renal hemodynamics and segmental sodium handling were evaluated using inulin, para-aminohippuric acid, sodium, and lithium clearances. Plasma atrial natriuretic peptide and renal dopamine were also monitored.
What was found
Low- and high-dose insulin infusions decreased sodium clearance from a baseline of 1.6 ± 0.1 ml/min to 1.2 ± 0.1 ml/min and 1.0 ± 0.1 ml/min, respectively. Both levels of hyperinsulinemia increased distal tubular sodium reabsorption. Concurrently, proximal tubular sodium reabsorption showed a time- and dose-dependent decline. Hyperinsulinemia caused dose- and time-dependent increases in renal plasma flow, while plasma atrial natriuretic peptide and renal dopamine levels showed no significant changes.
Why it matters
This study indicates that acute insulin elevation stimulates distal nephron sodium reabsorption, while simultaneously triggering a compensatory decrease in proximal reabsorption that may be mediated by renal vasodilation.
Limits
The study was very small (n = 10) and exclusively included healthy males. It only examined acute, short-term responses during clamp conditions without evaluating long-term effects or applicability to females, diabetic patients, or hypertensive populations.
Cited by
- supports Insulin is a powerful sodium-retaining hormone in the body.