Haemodynamic effects of intact digoxin antibody and its Fab fragments in experimental hypertension

Area of Science:

• Pharmacology
• Cardiovascular Physiology
• Nephrology

Background:

• Digoxin antibodies are used to treat digoxin toxicity.
• Hypertension is a complex condition with various contributing factors.
• The role of endogenous digitalis-like factors in blood pressure regulation is debated.

Purpose of the Study:

• To investigate the effects of digoxin antibody and its Fab fragment on blood pressure in different rat models of hypertension.
• To determine the role of endogenous digitalis-like factors in blood pressure regulation.

Main Methods:

• Administered intact digoxin antibody and its Fab fragment intravenously to conscious spontaneously hypertensive rats (SHR) and deoxycorticosterone hypertensive rats.
• Measured blood pressure, cardiac output, and total peripheral resistance.
• Utilized in vitro binding assays to assess antibody-antigen interactions.

Main Results:

• Fab fragments bound digoxin, digitoxin, and ouabain more efficiently than intact antibodies in vitro.
• Fab fragments prevented digoxin-induced increases in total peripheral resistance but did not alter baseline hemodynamics in hypertensive rats.
• Intact digoxin antibodies lowered blood pressure in SHR and deoxycorticosterone hypertensive rats by decreasing total peripheral resistance.

Conclusions:

• The Fc domain of digoxin antibodies contributes to blood pressure reduction in hypertensive rats.
• Endogenous digitalis-like factors are unlikely to play a significant role in salt-loaded hypertension in rats.