Objective: Calcium channel blockers posseses vasodilating action but there is no evidence to our knowledge about vasodilating effect on different arterial vesels. The aim of this investigation was to ascertain the reactions of large arteries and precapillary resistance vessels during treatment with sustained-released Verapamil (Flamon-240 SR, Mepha Ltd).

Design and methods: 30 essential hypertensives (WHO II) aged between 40–65 yrs received 2 months′ treatment with Flamon-240 SR 1–2 tablets daily. Blood pressure was determined auscultatory. Cardiac output (CO) and systemic vascular resistance (SVR) were derived from echocardiographic findings. Distensibility (D) of forearm large arteries was calculated as a ratio between volume pulse amplitude and pulse pressure. Forearm vascular resistance (FVR) was calculated from data on mean arterial pressure and forearm blood flow measured by venous occlusion plethysmography.

Results: It was stated that Verapamil significantly reduces systolic (−18,8±1,9 mmHg), diastolic (−8,7±1,2 mmHg), mean (−13,7±1,6 mmHg) and pulse (−12,5±1,5 mmHg) pressure. D of forearm large arteries in all investigated patients increases by 53±4%, whereas FVR did not change uniformly. In the case when hypotensive effect was caused by a decrease in CO, FVR did not change, but in the case when hypotensive effect was ensured by a decrease in SVR, the inverse relationship existed between changes in SVR and FVR (r = −0,6).

Conclusions: During effective treatment of essential hypertensives with Verapamil contractile activity of forearm large arteries always decreases, whereas precapillary vessels obviously are involved in counterregulation and this masks direct vasodilator effect of Verapamil on arterial smooth muscles.