Aims: 

Coronary perfusion decreases with aging and hypertension. Several effects of aging and hypertension on the resistance artery wall have been described, but their network remodeling is less described. Thus we aimed to quantitatively analyze the characteristic of aging- and hypertension-induced alterations of the coronary resistance artery network.

Methods: 

Seven old and 8 young male rats, and 7 chronically Ang II infused hypertensive and 8 control female rats were investigated. The whole resistance artery network of the left anterior descendent coronary artery was prepared, in situ perfused with Krebs solution, and recorded by videomicroscopy. The network was divided into branching units and into segments, these latter were further divided into 50 micrometer ring units. A coordinate system was positioned above the heart, and the locations, directions and diameters of the ring units were determined. Their statistical distribution on the heart surface was statistically analyzed.

Results: 

Broken course of the main branch and multiple branching are typical findings both in the aging and in the hypertensive networks. Large branches frequently originate at high angle, small branches at low angle, features rarely seen in normal, young networks. Dilation of the branches close to the orifice was accompanied by a reduction of the number of small diameter components (rarefaction). The diameter/frequency plot characteristically altered, with many similarities in the both groups.

Conclusion: 

It seems to be characteristic, that in both situations originally thin branches thickened, and originally thick branches thinned, their courses in the network deviating from the typical young pattern. These morphological alterations may cause the decreased ventricular wall perfusion typical for the aged and for the hypertensive. Hypertension significantly reduced the network structure of these vessels. The observed alterations elevate the hemodynamic resistance and can be evaluated as an adaptive process to the hypertension.