Changes in the microcirculation of the intact rat heart after iodinated and gadolinium-containing contrast media

A new model was developed to study microcirculation in the intact heart of the anesthetized rat, and the effects of roentgenography and magnetic resonance imaging contrast media were investigated.

Roentgenography contrast media (600 mg iodine/kg), gadopentetate (0.25 mmol/kg), or physiological saline were injected intraarterially into anesthetized rats (N = 10) whose chests had been opened in a pressurized container. The effects on arterial and venous vasomotion and microhemodynamics of the capillary network were determined in vivo by combined incidental light-fluoroscopic microscopy using continuous 35-mm cine film and video recordings from 5 minutes before until 20 minutes after injection. The amplitude and frequency spectra were evaluated according to the Prony method and by Fourier analysis. Additionally, the number of perfused vessel bifurcations were counted.

Gadopentetate exhibited no effects on microcirculation, and diatrizoate exhibited the largest ones. The deformation of the vasomotion spectrum reached 28%, and bifurcations were reduced by 21%. The effects were reversible within 10 minutes of injection. Iotrolan showed minimal disturbance. The other contrast media (iopromide, iopamidol, ioxaglate) fell between these two extremes.

High-osmolar ionic roentgenography contrast media resulted in a transient deregulation of vasomotion and in a disturbed microcirculation in the rat heart. Isotonic or low-osmolar nonionic roentgenography contrast media or gadopentetate did not show this effect or showed it only to a minimal extent.