Undergraduates
Several project are ongoing in the laboratory that are available for undergraduates. That research can be done for credit in Dr Kurjiaka's Laboratory.
Techniques to be Employed
HistologyHistochemistry
Immunohistochemistry
Microscopy
Image Quantification (imaging and analysis)
Dose Response Curves
This project has many components and is very amenable to undergraduate research. People involved in this project will learn some histology, histochemistry and immunohistochemistry. Histology is the fixing, sectioning, staining and quantification of larger artery morphology. The staining will involve staining smooth muscle cells and extracellular matrix to determine whether either of those components of the vasculature are affected by hypertension. Stereological techniques will be used to determine whether any gross changes in vessel structure have occurred in the hypertensive hamster (many studies on other animal species including humans have shown that the vessel wall thickens and lumenal diameter decreases). Further, those same vessel can be stained with antibodies for the gap junctions proteins (connexins 40, 43 and 37: Cx40, Cx43 and Cx37). This data will provide some indication as to whether Cx expression can be associated with vascular morphology changes.
Previous studies have demonstrate a decrease in arteriole density in the microvasculature of hypertensive rats (rarefaction). This decrease in arteriole density could have implications for oxygen delivery to tissue. The diffusion gradient required to perfusion the tissue would be increased by a reduction in arteriolar density. This could predispose metabolically active tissue to ischemia thereby reducing the exercise capacity of a hypertensive.
This inbred strain of hamsters was developed in Nova Scotia at Canadian Hybrid Farms by Ted White. At 10 weeks of age, the blood pressure in these animals increased. Pressure have been observed to be elevated above 240 mmHg. However, the source of the hypertension in these animals is not known. Thus, some assessment of the source of the hypertension remains to be performed. At the same time, we have been concerned that a proportion of these hamsters may also be diabetic. This would provide an excellent model for the study of cardiovascular complications to syndrome X. Our vasomotor work suggests the elevation in blodo pressure may involve differences in vascular responses to angiotensin II.
Graduate Students
Many opportunities that include those for undergraduates with the addition of the in situ microvascular preparation. The hamster has been used extensively as a model for the study of the microvasculature. This preparation requires ~1.5 hrs of surgery to isolate and cannulate a feed artery. In particular, I am interested in understanding whether vasomotor responses of the feed artery are affected by the presence of hypertension. To date, we have found responses that rely on gap junctions (conducted vasomotor responses) and those to angiotensin II are altered in the hypertensive hamster. Interestingly, responses to acetylcholine, bradykinin and adenosine are not altered. In fact, bradykinin induces minimal dilation as does adenosine. Further, dilatory responses to nitric oxide donors are also severely compromised in both normo and hypertensive hamsters. Thus, it would appear that vascular responses that rely on nitric oxide are diminished in the hamster and is not specifically due to the hypertension. Whether this involves a decrease in the release of nitric oxide or a diminished responses of the soluble cGMP tpo nitric oxide (or both) remains to be determined.