Related Experiment Videos
Catamenial variations in erythrocyte sodium-lithium countertransport and blood pressure
G I Adebayo1, L Hemeryck, M Hall
1Department of Therapeutics, Trinity Centre for Health Sciences, St James's Hospital, Dublin, Republic of Ireland.
Insights
Sodium-lithium countertransport activity in erythrocytes varies across the menstrual cycle, being lowest during the midcycle phase. This finding suggests standardizing blood sampling times for future studies on this transport system in females.
Area of Science:
- Physiology
- Endocrinology
- Cardiovascular Research
Background:
- Sodium-lithium countertransport is an indicator of cellular sodium transport.
- Hormonal fluctuations during the menstrual cycle may influence physiological parameters.
- Understanding these variations is crucial for accurate health assessments in women.
Purpose of the Study:
- To investigate the temporal changes in sodium-lithium countertransport activity in erythrocytes throughout the menstrual cycle.
- To examine the relationship between these changes and blood pressure variations.
- To correlate transport activity with plasma levels of estradiol and progesterone.
Main Methods:
- A longitudinal study was conducted on 22 healthy females across menstrual, midcycle, and luteal phases.
- Erythrocyte sodium-lithium countertransport activity and blood pressure were measured.
- Plasma estradiol and progesterone levels were quantified.
Main Results:
- Sodium-lithium countertransport activity was significantly lower in the midcycle phase compared to menstrual and luteal phases.
- Diastolic blood pressure exhibited a similar pattern, being lower in the midcycle phase.
- Progesterone levels positively correlated with sodium-lithium countertransport activity during the luteal phase.
Conclusions:
- Sodium-lithium countertransport activity demonstrates significant variation throughout the menstrual cycle (catamenial variation).
- Diastolic blood pressure fluctuations parallel the changes in sodium-lithium countertransport activity.
- Standardization of blood sampling relative to the menstrual cycle phase is recommended for future studies assessing this transport system in females.
Abstract:
1. We undertook a temporal study of external sodium-stimulated lithium efflux (sodium-lithium countertransport) in erythrocytes and blood pressure by measuring these two parameters in three phases of the menstrual cycle (menstrual, midcycle and luteal phases) in 22 healthy, non-medicated females with regular menstrual cycles. Plasma oestradiol and progesterone levels were also determined. 2. Sodium-lithium countertransport activity (activity in 140 mmol/l external NaCl) in the midcycle phase (0.176 +/- 0.017 mmol h-1 l-1 of cells) was lower than in the menstrual (0.192 +/- 0.016 mmol h-1 l-1 of cells, P < 0.030) and luteal (0.203 +/- 0.018 mmol h-1 l-1 of cells, P < 0.030) phases. The Vmax of the transporter changed similarly but the K(m) was unaltered. 3. The plasma oestradiol level was 628.9 +/- 39.1 pmol/l in the midcycle phase, higher than in the menstrual (232 +/- 18.5 pmol/l, P < 0.001) and luteal (372.5 +/- 28.1 pmol/l, P < 0.001) phases. The progesterone level was 28.6 +/- 2.1 nmol/l in the luteal phase, and values were lower in the menstrual (2.5 +/- 0.3 nmol/l, P < 0.001) and midcycle (2.8 +/- 0.4 nmol/l, P < 0.001) phases. 4. There was no correlation between plasma oestradiol and sodium-lithium countertransport activity or Vmax during the menstrual cycle, but plasma progesterone was positively correlated with sodium-lithium countertransport activity (r = 0.478, P < 0.025, n = 22) and Vmax (r = 0.551, P < 0.045, n = 14) in the luteal phase. 5. Systolic blood pressure did not change significantly during the menstrual cycle. However, the diastolic pressure showed variation similar to that in sodium-lithium countertransport activity/Vmax, its midcycle value of 66.6 +/- 1.4 mmHg being lower than that in the luteal (71.6 +/- 1.3 mmHg, P < 0.025) and menstrual (70.6 +/- 1.4 mmHg, P < 0.025) phases. 6. We conclude that sodium-lithium countertransport activity exhibits catamenial variation. Therefore we suggest, given this observation, that blood sampling for the assessment of the state of activity of the transport system be standardized in relation to a phase of the menstrual cycle in future studies involving females.