Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

We have previously observed that blood vessels from 4-week-old spontaneously hypertensive rats (SHR) and normotensive WKY shortened between 30-40%(SHR=29±4%,WKY=39±3%) when excised. This process causes thickening of the vessel wall and affects lumen diameter. We therefore studied different fixation techniques on the structure of maximally-relaxed large mesenteric arteries from 4-week-old SHR and WKY. Vessels were fixed either in vitro on micropipettes at their in vivo pressure of 70 mmHg, or in situ by perfusion at a flow rate of 1mL/min/100 g of body weight. Vessels were then measured under confocal microscopy. No significant difference in lumen area was found between in vitro and in situ fixed vessels. Medial volume per unit length was also similar between in vitro and in situ fixed arteries, but was significantly greater in SHR than WKY. Thus our in situ fixation method preserved lumen size as compared to vessels fixed at in vivo pressure, and these pressurized vessels had not shortened since they showed similar medial volume per unit length as in in situ fixed arteries. Closer examination of the in situ fixation showed that perfusion pressures were increased with the introduction of the fixative, causing an increase in lumen diameter which eventually attained 85% in SHR, and 91% in WKY of their in vivo lumen diameter. We conclude that both fixation methods provide adequate preservation of in vivo artery structure and eliminate distortions introduced by retraction of vessels upon excision. (Supported by the Heart and Stroke Foundation of Ontario)

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Presentation Number SAdickhout0449
Keywords: hypertension, blood vessel, technique, morphometry