High resolution 23Na-nuclear magnetic resonance study of stroke-prone spontaneously hypertensive rat erythrocytes

The control of vascular smooth muscle function: my life-long learning and continuous discovery with Professor E.E. Daniel

This communication is neither a comprehensive review of my research, nor a description about my recent new original scientific findings in smooth muscle or in cell Ca2+. For that intention, I will choose to publish via a regular channel, certainly not in this special edition. My intention is to take this opportunity to recapitulate Dr. Daniel's thoughts and spirits through the progress of my research, teaching, and personal development at McMaster University, stemming largely from Dr. Daniel's life-long interest in the regulation of Ca2+ in the control of smooth muscle function, specifically the vascular smooth muscle. Being a culturally adsorbent person, I am sure that my thoughts and behavior must have been substantially influenced by Dr. Daniel over 27 years of our collaboration. His influence may have molded me into whom and what I am today, both socially and scientifically. Equally, I may also have influenced him in some particular or peculiar way. Dr. Daniel's academic contribution is globally well known for, but not limited to, his insightful and productive research in smooth muscle, but also for his effective application of problem-based learning to education in pharmacology and his influence on students and colleagues.

Comparative study on free radical injury in the endothelium of SHR and WKY aorta

1. Using 13 week old SHR and WKY rats, aortic endothelial injury was examined after tert-butylhydroperoxide (t-BOOH) perfusion. 2. ESR analysis revealed a hydroxyl radical adducts in the perfusate after t-BOOH perfusion. 3. After t-BOOH perfusion, endothelial changes such as cauliflower-like blebs and crater-like holes were frequently observed in the SHR aorta, but rarely seen in the WKY aorta. 4. X-ray spectra revealed the cerium perhydroxide deposition on the surface of endothelial cells of the SHR aorta. 5. These findings indicate that free radical injury is much more intense in the endothelial cells of SHR than in those in WKY.

Erythrocyte Na+/K+ ATPase activity measured with 23Na NMR

A 23Na NMR assay for measurement of erythrocyte Na+/K+ ATPase activity is presented. Using the nonpermeant shift reagent dysprosium tripolyphosphate the signals of intra- and extracellular sodium are separated, enabling measurement of sodium fluxes nondestructively, without the need to physically separate the cells from their environment. By increasing membrane permeability with nystatin we have shown that the assay allows the detection of differences in membrane permeability. With low doses of nystatin the ouabain-sensitive sodium flux increased more than twofold. With high doses of nystatin the Na+/K+ pump could not prevent an almost total equilibration of intra- and extracellular sodium. All sodium that entered the cells remained NMR visible, proving that sodium influx can be measured quantitatively. 31P NMR spectra taken before and after the assay revealed a slight acidification of the cells and no significant change in ATP concentration. No evidence of Dy3+ entering the cell was observed.