CELLULAR ASPECTS OF VASCULAR REMODELING IN HYPERTENSION REVEALED BY CONFOCAL MICROSCOPY

Cellular aspects of remodeling in intact arteries have not been fully investigated, mainly due to the lack of an appropriate methodology tha t allows for simple measurements. The aim of this study was to develop a method based on laser scanning confocal microscopy (LSCM), compare it with previous methodology, and apply it to the study of remodeling in hypertension. The morphology of mesenteric resistance arteries from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY) was determined with wire myography on one segment with a s tandardized diameter setting (0.9(d100)) and with perfusion myography on a second segment from the same artery at the calculated equivalent pressure. The second segments were stained with the nuclear dye Hoechs t 33342 (live tissue) or propidium iodide (fixed tissue) and measured with LSCM and MetaMorph software. Compared with wire myography, perfus ion myography showed similar differences from those previously reporte d. Compared with LSCM, perfusion myography showed a similar lumen but significantly smaller wall thickness in both live and fixed tissue, pr obably due to measurement underestimation. In the study with LSCM, art eries from SHRSP compared with those from WKY showed (1) reduced lumen , (2) altered cell density that was significantly increased in the adv entitia, decreased in the media, and unchanged in the intima, (3) sign ificantly increased medial volume, (4) significantly smaller endotheli al cell nuclei, and (5) adventitial-like cells in the media. We conclu de that (1) LSCM is a reliable and straightforward method to study mor phology in intact vessels, (2) it provides new information on the cell ular changes in remodeling, (3) adventitia might play an active role i n the process of remodeling in hypertension, and (4) endothelium ''rem odels'' in hypertension.