[Effects of isosorbide dinitrate and diltiazem used alone or combined on arterial hemodynamic and viscoelastic...

An experimental model of simultaneous recording of aortic pressure and flow and vascular diameter at the entrance to a limited territory of systemic circulation has been developed in the rabbit. A system of data acquisitions and treatment has also been perfected to evaluate the different parietal viscoelastic parameters of arterial flow in capacitance and resistance arteries. This model was used to study the pharmacodynamic effects of two vasodilator drugs, isosorbide dinitrate (ISDN) and diltiazem (DILT), administered alone or in association (ISDN + DILT) by slow intravenous infusion over 30 minutes at dosages chosen to induce comparable hypotension of about 10%. Under these conditions, the effects of ISDN, DILT and ISDN + DILT on resistance parameters were slightly different. The ISDN had no marked effect on mean aortic flow (Qm) apart from a slight decrease after 10 minutes infusion (-10.4 +/- 3.8%, p less than 0.05). On the other hand, DILT alone or in association with IDN was associated with a significant increase in Qm (DILT: +8.5 +/- 0.8%, p less than 0.001; ISDN + DILT: +9.7 +/- 2.1%, p less than 0.01). This explains the absence of a significant effect of ISDN on peripheral resistance (PR) or entrance impedance (Zc) of the vascular bed. Conversely, the effects of DILT and ISDN + DILT on these parameters were very marked (DILT:RP = -17.2 +/- 0.9%, p less than 0.001; Zc = -8.2 +/- 0.5%, p less than 0.001; ISDN + DILT: RP = -16 +/- 1.4%, p less than 0.001; Zc = -8.0 +/- 0.4%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)