Reduction in extracellular Ca2+ attenuates endothelium-dependent relaxation more than nitroprusside-induced relaxation.

AIM: To quantitatively assess the effect of lowering external Ca(2+) ([Ca(2+)](o)) on both endothelium-dependent and -independent relaxations in rabbit aorta. METHODS: Isometric contractions and relaxations of isolated aortae were recorded. When assessing the effect of reduced [Ca(2+)](o) on relaxations, the normal [Ca(2+)](o) solution was substituted with one of the reduced [Ca(2+)](o) solutions for one aorta, while a paired aorta was replenished with normal [Ca(2+)](o) solution. RESULTS: The extent of acetylcholine (ACh)-induced relaxation, which is dependent on an intact endothelium, is time-dependent, and inversely related to [Ca(2+)](o) in a range of 0.02-2 mmol/L. ACh-induced relaxations were not significantly altered by the magnitude of the precontraction induced by PGF(2alpha). Nitroprusside-induced relaxations, which are independent of the endothelium, are also attenuated by reduced [Ca(2+)](o). Relaxant responses to ACh were significantly more susceptible to reduced [Ca(2+)](o) than nitroprusside-induced relaxations. A maximally effective relaxing concentration of D600, an L-type Ca channel blocker methoxyverapamil, (10(-5) mol/L) attenuated ACh-induced relaxations, whereas nitroprusside-induced relaxations were unaffected by D600. CONCLUSION: Thus, endothelium-dependent relaxation is more dependent on [Ca(2+)](o) than endothelium-independent relaxation, and it seems likely that [Ca(2+)](o) plays an important role not only in contractile processes, but also in relaxant processes as well.

Addressing medical school diversity through an undergraduate partnership at Texas A&M Health Science Center: a blueprint for success.

Imperative to increasing diversity in the physician workforce is increasing the pool of qualified underrepresented minority applicants to medical schools. With this goal in mind, the Texas A&M Health Science Center College of Medicine (A&M College of Medicine) has partnered with Prairie View A&M University (PVAMU), a historically black college and university that is a component of the Texas A&M university system, to develop the undergraduate medical academy (UMA). The UMA was established by legislative mandate in 2003 and is a state-funded program. The authors describe the development of partnership between the A&M College of Medicine and PVAMU, focusing on the key attributes that have been identified for success. The administrative structure of the UMA ensures that the presidents of the two institutions collaborate to address issues of program oversight and facilitates a direct relationship between the dean and associate dean for academic affairs of A&M College of Medicine and the director of the UMA to define the program objectives and structure. The authors delineate the admission process to the UMA, as well as the academic requirements of the program. Students attend lecture series during the academic year and participate in summer programs on the A&M College of Medicine campus in addition to receiving intensive academic counseling and opportunities for tutoring in several subjects. The authors also describe the initial success in medical school admissions for UMA students. This partnership provides a model blueprint that can be adopted and adapted by other medical schools focused on increasing diversity in medicine.