Eight normal male Beagle dogs received 0.7 mmol Na+/kg/day for 5 weeks and 4.0 mmol Na+/kg/day in one 3 week control period preceding and another similar period following the low sodium period. The dogs received 6.8 mmol K+/kg/day throughout the study. The median plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were higher in the low sodium period than in the following control period (0.67 versus 0.28 ng/ml/h, p < 0.0001) and (204 versus 31 pg/ml, p < 0.0001). PRA and PAC quickly stabilized on a new steady level in response to altered intake of sodium chloride. The angiotensin-converting enzyme (ACE) activity was not changed by the altered intake of sodium chloride. The plasma concentrations of sodium and chloride were increased during the low sodium period. This could be due to an indirect effect of the high potassium intake of the dogs. Potassium leads to an increased secretion of aldosterone and thereby to an increased retention of sodium and chloride in the kidney. The possible implications of a high potassium content in a low sodium diet are discussed.
Otte normale beagle hunde indtog 0.7 mmol Na+/kg/dag i en 5 ugers periode og 4.0 mmol Na+/kg/dag i en 3 ugers kontrol penode før og en ef-ter lav-natrium perioden. Hundene indtog 6.8 mmol K+/kg/dag i hele perioden.
Medianværdien af plasma renin aktiviteten (PRA) og plasma aldosteron koncentrationen (PAC) var højere ι lav-natrium perioden end ι den efterføl-gende kontrol periode (0.67 versus 0.28 ng/ml/h, Ρ < 0.0001) og (204 versus 31 pg/ml, Ρ < 0.0001). PRA og
PAC lndstillede sig hurtigt på et nyt stabilt niveau ef-ter ændret natrium lndtag. Angiotensin-converting enzyme (ACE) aktiviteten ændrede sig lkke som følge af det ændrede natrium indtag. Plasma koncentrationerne af natrium og klorid var højere ι lav-natrium perioden sammenlignet med de to kontrol perioder. Dette skyldtes muligvis en lndi-rekte effekt af det høje kalium indtag. Kalium fører til en forøget sekretion af aldosteron og dermed til en øget retention af natrium og klorid ι nyrerne. Mulige betydninger af et højt kalium indhold ι lavnatrium diæter diskuteres.