In terms of the research interests of the authors, the work undertaken by their own students has focused on pharmacologically characterizing the contribution of four different β-adrenoceptor subtypes to cardiac contractility. The β-adrenoceptor family comprises members of the superfamily of protein receptors called G protein-coupled receptors (GPCRs). The Gs version of this protein links to a receptor (the β1-adrenoceptor and often the β2-adrenoceptor) that mediates stimulation of the activity of cardiac cells in terms of positive force generation, rate of contraction, and speed of relaxation (positive inotropy, chronotropy, and lusitropy, respectively). It does this largely through activation of a membrane-bound enzyme, adenylate cyclase, which produces increased amounts of an intracellular signaling molecule called cAMP. cAMP goes on to stimulate the production of more PKA, a molecule that can phosphorylate a number of cellular protein targets to change their function by this change in structure. Targets include the L-type Ca2+ channel (causing the entry of more Ca2+ into the cell, thus facilitating the positive inotropic and chronotropic changes) and phospholamban, a protein that regulates Ca2+ reuptake into the intracellular store for Ca2+, the sarcoplasmic reticulum (facilitating the positive lusitropic changes). There also exists a Gi version, which mediates negative inotropic and chronotropic effects (via the β3-adrenoceptor physiologically and the β2-adrenoceptor pathophysiologically in heart failure). In cardiac cells, this is done by the stimulation of a cytosolic enzyme, guanylate cyclase, which generates increased amounts of cGMP and consequently PKG. Phosphorylation events mediated by PKG include a reduction in the opening probability of the L-type Ca2+ channel (facilitating the negative inotropic and chronotropic changes).
Apart from the chronotropic analyses possible in spontaneously beating cardiac cell cultures, students have also undertaken biochemical studies looking at cAMP and PKA mobilization due to various β-adrenoceptor agonists. In addition, atomic absorbance analyses of media samples to look at Mg2+ efflux out of these cells in response to β-adrenoceptor stimulation has also been performed. Thus, it is evident that once students are routinely able to isolate spontaneously beating cells, there are a plethora of research avenues that could be pursued depending on their own interests and level of engagement.
Furthermore, despite the apparent simplicity and robustness of this preparation, novel data can still be generated (
7). Therefore, this technique is an ideal tool to give students an initial insight into the research process from constructing hypotheses, elaborating methods, and obtaining data to critically analyzing and potentially reporting their findings in peer-reviewed journals. This inclusion of undergraduate students as partners in collaborative research endeavors has been much discussed in the United Kingdom (UK) context (for a review, see Ref.
15) and is an ever-increasing feature of the student experience at UK Higher Education Institutions.
A typical trajectory for undergraduate students learning this technique in the authors’ own laboratories would first involve sessions on aseptic techniques and then the mechanics of enzymatically isolating viable populations of beating cardiac cells. Students usually observe the cell isolation procedure being conducted by their project supervisor on two or three separate occasions. They are told to write detailed notes of the procedure as it is being performed and then to come up with their own step-by-step guide to this method. Having produced their own guide, students undertake the cell isolation themselves with their project supervisor in close attendance offering verbal guidance and physical aid if necessary. This stage is repeated as often is necessary to convince the project supervisor that the students are competent enough to undertake the cell isolation procedure alone. In practice, this usually takes no longer than three supervised cell isolations. After this time, students are able to work unaided and independently of the project supervisor.
Once this has been successfully achieved and beating cells are routinely obtained, students are encouraged to design their own experiments around a suitable testable hypothesis. After data has been gathered, students analyze their data, subject it to statistical analysis, and present it graphically as plots and graphs. Finally, students are enjoined to discuss their own results with those already existing in the literature that might have relevance to the work they have completed. In the authors’ settings, these projects are finally presented by the students in the form of oral or poster presentations to an audience of peers and academic assessors.
