Increased capillary permeability for plasma proteins in oral contraceptive users

Area of Science:

• Physiology
• Pharmacology

Background:

• Transcapillary fluid balance is crucial for maintaining homeostasis.
• Oral contraceptives (OCs) are widely used, necessitating understanding of their physiological effects.

Purpose of the Study:

• To investigate the impact of a monophasic oral contraceptive on transcapillary fluid balance in women.
• To determine changes in interstitial and plasma pressures and related biochemical markers during OC use.

Main Methods:

• Monophasic oral contraceptive (desogestrel 0.15 mg, ethinylestradiol 0.03 mg) administered to eleven women.
• Interstitial colloid osmotic pressure measured using the "wick" method.
• Interstitial hydrostatic pressure measured using the "wick-in-needle" method in subcutaneous tissue.

Main Results:

• Significant decrease in plasma colloid osmotic pressure, serum albumin, and total protein concentration.
• Reduced hemoglobin and hematocrit levels observed.
• Increased foot volume and reduced colloid osmotic pressure gradient (plasma-interstitium) noted, while blood pressure and body weight remained stable.

Conclusions:

• Oral contraceptive use leads to increased plasma volume and capillary permeability to plasma proteins.
• The estrogen component of the oral contraceptive is suggested as the cause of these observed fluid balance alterations.