Contradictory Effects of beta 1-and alpha 1-Aderenergic Receptor Blockers on Cardio-Ankle Vascular Stiffness Index (CAVI) - CAVI is Independent of Blood Pressure

Aim: The cardio-ankle vascular stiffness index (CAVI) is a new parameter that reflects the stiffness of the aorta, femoral artery and tibial artery as a whole. One of its conspicuous features is that CAVI is independent of blood pressure at measuring time, theoretically. But, it has not been experimentally proved yet. For confirmation, pharmacological studies were performed comparing with brachial-ankle pulse wave velocity (baPWV). Methods: Used drugs were a beta 1-adrenoceptor blocker, metoprorol and an alpha 1-adrenoceptor blocker doxazosin. Both were administered to 12 healthy volunteer men. CAVI and baPWV were measured every one hour for 6 hours using VaSera. Results: When metoprolol (80 mg) was administered to 12 healthy volunteer men, systolic blood pressure decreased from 131.4 +/- 4.5 to118.3 +/- 4.1 mmHg (mean +/- SE) (p< 0.05) at the 3rd hour, and diastolic blood pressure decreased from 85.3 +/- 4.0 to 75.3 +/- 3.0mmHg (p< 0.05). baPWV decreased from 13.93 +/- 0.46 to 12.46 +/- 0.49 m/sec (p< 0.05), significantly, but CAVI did not change (8.16 +/- 0.29 to 8.24 +/- 0.27) (p = 0.449). Delta baPWV at each time was significantly correlated with both Delta systolic and Delta diastolic blood pressures, but Delta CAVI was not correlated with either Delta blood pressure. When doxazosin (4 mg) was administered to the same men, systolic blood pressure decreased from 130.2 +/- 4.6 to117.2 +/- 4.8 mmHg (p< 0.05) at the 3rd hour. Diastolic blood pressure also decreased from 85.1 +/- 4.1 to 74.2 +/- 3.9 mmHg (p< 0.05). baPWV decreased from 13.98 +/- 0.68 to 12.25 +/- 0.53 m/sec (p< 0.05), significantly. CAVI also decreased from 8.15 +/- 0.28 to 7.18 +/- 0.37 (p< 0.05), significantly. Conclusion: These results suggested that CAVI was not affected by blood pressure at the measuring time directly, but affected by the changes of contractility of smooth muscle cells.