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Pressor response to stress and exercise in the young: intracellular ion content relationships and prognostic
E Ambrosioni1, C Borghi, F V Costa
1Cattedra e Servizio di Farmacologia Clinica, Università di Bologna, Italy.
Insights
Intracellular sodium (Nai) and potassium (Ki) levels impact blood pressure and vascular resistance in individuals prone to hypertension. High Nai predicts future hypertension development, while Ki influences diastolic blood pressure.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Cellular Ion Transport
Background:
- Intracellular sodium (Nai) and potassium (Ki) are critical for cellular function.
- Altered ion content is implicated in hypertension development and progression.
- Peripheral hemodynamics and blood pressure regulation are influenced by ion balance.
Purpose of the Study:
- To investigate the relationship between intracellular Na+ and K+ content, blood pressure, and peripheral hemodynamics.
- To explore the role of intracellular ions in the pressor response to stress and exercise.
- To assess the predictive value of intracellular Na+ for future hypertension development.
Main Methods:
- Studied young subjects with a family history of hypertension or borderline hypertension.
- Measured intracellular Na+ (Nai) and K+ (Ki) content.
- Assessed blood pressure and peripheral hemodynamics, including forearm vascular resistance (FVR), during rest, stress, and exercise (handgrip test).
- Monitored subjects for hypertension development over five years.
Main Results:
- Direct correlation found between Nai and pressor response to stress/exercise.
- Low-salt diet decreased Nai and pressor response.
- Ki inversely related to diastolic blood pressure (DBP) at rest and during stimulation.
- High Nai/Ki ratio linked to increased forearm vascular resistance (FVR) during exercise and impaired FVR decrease post-exercise.
- Acute salt loading increased FVR proportionally to Nai in borderline subjects.
- Subjects with high Nai and borderline hypertension had a 31% risk of developing sustained hypertension within five years, versus 0% for those with normal Nai.
Conclusions:
- Intracellular ion content significantly influences blood pressure regulation and hemodynamic responses.
- Altered Nai/Ki ratio may impair vasodilatory capacity, contributing to hypertension.
- Elevated intracellular Na+ content serves as a significant predictor of future sustained hypertension in at-risk individuals.
Abstract:
The relationships between intracellular Na+ (Nai) and K+ (Ki) content, blood pressure and peripheral hemodynamics were investigated in young subjects with a family history of hypertension or with borderline hypertension. A direct correlation was found between Nai and pressor response to stress and exercise; after a short-term low-salt diet a parallel decrease was found in Nai and in pressor response to provocative tests. On the contrary, Ki was inversely related to diastolic blood pressure (DBP) both a rest and during mental and physical stimulation. The mechanism by which alterations in intracellular ion content lead to hemodynamic changes may be mediated by a reduced vasodilatory capacity. In fact, during handgrip testing, the increase in forearm vascular resistance (FVR) was directly related to the Nai/Ki ratio while after the exercise, FVR decrease in subjects with normal Nai/Ki and increases in those subjects with high Nak/Ki. In borderline subjects FVR at rest was inversely related to Nai but acute salt loading causes an increase in FVR proportional to Nai. These observations suggest that in subjects with borderline hypertension FVR at rest is normal perhaps as a response to a high cardiac output; however, a further hemodynamic load (salt loading) causes an increase in FVR directly related to Nai and inversely related to Ki. The study of Nai can also give useful information about the risk of developing sustained hypertension. While no subject with borderline hypertension with normal Nai developed hypertension within five years, 31% of those subjects with high Nai developed hypertension after five years.