A Pilot Study on the Use of Lecture Tools to Enhance the Teaching of Pharmacokinetics and Pharmacodynamics

Pharmacokinetics and pharmacodynamics are essential topics contained within the medical curriculum and are highly amenable to active-learning approaches. In this pilot study, we incorporated Lecture Tools, a cloud-based audience response system, into a lecture-based graduate course. Lecture Tools was used by both the instructors and the students during peer presentations. Advantages noted by the instructors include the versatility of the questions that can be presented and the ease with which student assessment can be conducted. Student surveys revealed that, overall, the use of Lecture Tools enhanced student attentiveness and engagement and facilitated student participation in questions and answers. Some disadvantages were observed and include the increased time required for lecture presentations. In summary, our results indicate that Lecture Tools can be effectively used in a medical education setting

The α1D-adrenergic receptor is expressed intracellularly and coupled to increases in intracellular calcium and reactive oxygen species in human aortic smooth muscle cells

Background: The cellular localization of the α1D-adrenergic receptor (α1D-AR) is controversial. Studies in heterologous cell systems have shown that this receptor is expressed in intracellular compartments. Other studies show that dimerization with other ARs promotes the cell surface expression of the α1D-AR. To assess the cellular localization in vascular smooth muscle cells, we developed an adenoviral vector for the efficient expression of a GFP labeled α1D-AR. We also measured cellular localization with immunocytochemistry. Intracellular calcium levels, measurement of reactive oxygen species and contraction of the rat aorta were used as measures of functional activity. Results: The adenovirally expressed α1D-AR was expressed in intracellular compartments in human aortic smooth muscle cells. The intracellular localization of the α1D-AR was also demonstrated with immunocytochemistry using an α1D-AR specific antibody. RT-PCR analysis detected mRNA transcripts corresponding to the α1A-α1B- and α1D-ARs in these aortic smooth muscle cells. Therefore, the presence of the other α1-ARs, and the potential for dimerization with these receptors, does not alter the intracellular expression of the α1D-AR. Despite the predominant intracellular localization in vascular smooth muscle cells, the α1D-AR remained signaling competent and mediated the phenylephrine-induced increases in intracellular calcium. The α1D-AR also was coupled to the generation of reactive oxygen species in smooth muscle cells. There is evidence from heterologous systems that the α1D-AR heterodimerizes with the β2-AR and that desensitization of the β2-AR results in α1D-AR desensitization. In the rat aorta, desensitization of the β2-AR had no effect on contractile responses mediated by the α1D-AR. Conclusion: Our results suggest that the dimerization of the α1D-AR with other ARs does not alter the cellular expression or functional response characteristics of the α1D-AR

Differential cardiovascular regulatory activities of the alpha1B- and alpha1D-adrenoceptor

ABSTRACT The regulation of cardiac and vascular function by th

The α\u3csub\u3e1D\u3c/sub\u3e-Adrenergic Receptor Is Expressed Intracellularly and Coupled to Increases in Intracellular Calcium and Reactive Oxygen Species in Human Aortic Smooth Muscle Cells

Background: The cellular localization of the α1D-adrenergic receptor (α1D-AR) is controversial. Studies in heterologous cell systems have shown that this receptor is expressed in intracellular compartments. Other studies show that dimerization with other ARs promotes the cell surface expression of the α1D-AR. To assess the cellular localization in vascular smooth muscle cells, we developed an adenoviral vector for the efficient expression of a GFP labeled α1D-AR. We also measured cellular localization with immunocytochemistry. Intracellular calcium levels, measurement of reactive oxygen species and contraction of the rat aorta were used as measures of functional activity. Results: The adenovirally expressed α1D-AR was expressed in intracellular compartments in human aortic smooth muscle cells. The intracellular localization of the α1D-AR was also demonstrated with immunocytochemistry using an α1D-AR specific antibody. RT-PCR analysis detected mRNA transcripts corresponding to the α1A-α1B- and α1D-ARs in these aortic smooth muscle cells. Therefore, the presence of the other α1-ARs, and the potential for dimerization with these receptors, does not alter the intracellular expression of the α1D-AR. Despite the predominant intracellular localization in vascular smooth muscle cells, the α1D-AR remained signaling competent and mediated the phenylephrine-induced increases in intracellular calcium. The α1D-AR also was coupled to the generation of reactive oxygen species in smooth muscle cells. There is evidence from heterologous systems that the α1D-AR heterodimerizes with the β2-AR and that desensitization of the β2-AR results in α1D-AR desensitization. In the rat aorta, desensitization of the β2-AR had no effect on contractile responses mediated by the α1D-AR. Conclusion: Our results suggest that the dimerization of the α1D-AR with other ARs does not alter the cellular expression or functional response characteristics of the α1D-AR

Immunocytochemical localization of the alpha-1B adrenergic receptor and the contribution of this and the other subtypes to vascular smooth muscle contraction: analysis with selective ligands and antisense

ABSTRACT The contribution of the alpha-1B adrenergic receptor (AR) to vascular smooth muscle contraction has been assessed using a combination of immunological, molecular biological and pharmacological approaches. A subtype-selective antibody detected alpha-1B immunoreactivity in the medial layer of the aorta, caudal, femoral, iliac, mesenteric resistance, renal and superior mesenteric arteries. Receptor protection assays and antisense oligonucleotides were used to assess the contribution of the alpha-1B AR to contraction. The alpha-1B AR was implicated in mediating the phenylephrine-induced contraction of the mesenteric resistance artery. The alpha-1D AR was implicated in mediating the contraction of the aorta, femoral, iliac and superior mesenteric arteries. Similarly, the alpha-1A AR was implicated in mediating contraction of the caudal and renal arteries. In vivo application of antisense oligonucleotides targeted to the translational start site of the alpha-1B AR had no effect on the phenylephrine-induced contraction of the femoral or renal arteries. In contrast, antisense oligonucleotides directed against the alpha-1D AR significantly inhibited the phenylephrine response in the femoral artery but had no effect on the renal artery. Application of alpha-1A AR antisense oligonucleotides inhibited the contraction of the renal artery without effect on the femoral artery. These data show that (1) alpha-1B AR immunoreactivity is widely distributed in the same peripheral arteries in which previous studies detected its mRNA, and (2) despite this distribution, receptor protection and antisense oligonucleotide studies indicate that the alpha-1B AR mediates the contraction of only the mesenteric resistance artery. The alpha-1 AR family is a member of the G proteincoupled superfamily of receptors. In analogy to bacteriorhodopsin, these receptors have the now very familiar proposed structure of seven transmembrane spanning domains connected by hydrophilic loops alternately exposed to the extracellular and intracellular environment. The structure of G protein-coupled receptors in general and alpha-1 ARs specifically have been the subject of several reviews (Bylund et a

and Nationallnstitutes of Health

ABSTRACT The interaction of agonists with alpha-i receptor subtypes sensitive and resistant to alkylation by a prazosin analog $1-(4- SZL-49} has been examined. In rat aortic nngs, SZL-49 (0.1 -1 0 nM) shifted the dose-response curves for norepinephnne and phenylephrine to the right. The curves were biphasic, consisting of high and low affinity components. At >1 0 nM, the curves became monophasic

The agonism and synergistic potentiation of weak partial agonists by triethylamine in α1-adrenergic receptor activation: Evidence for a salt bridge as the initiating process

α1-adrenergic receptor (AR) activation is thought to be initiated by disruption of a constraining interhelical salt bridge (Porter et al., 1996). Disruption of this salt bridge is achieved through a competition for the aspartic acid residue in transmembrane domain three by the protonated amine of the endogenous ligand norepinephrine and a lysine residue in transmembrane domain seven. To further test this hypothesis, we investigated the possibility that a simple amine could mimic an important functional group of the endogenous ligand and break this α1-AR ionic constraint leading to agonism. Triethylamine (TEA) was able to generate concentration-dependent increases of soluble inositol phosphates in COS-1 cells transiently transfected with the hamster α(1b)-AR and in Rat-1 fibroblasts stably transfected with the human α(1a)-AR subtype. TEA was also able to synergistically potentiate the second messenger production by weak partial α1-AR agonists and this effect was fully inhibited by the α1-AR antagonist prazosin. However, this synergistic potentiation was not observed for full α1-AR agonists. Instead, TEA caused a parallel rightward shift of the dose-response curve, consistent with the properties of competitive antagonism. TEA specifically bound to a single population of α1-ARs with a K(i) of 28.7 ± 4.7 mM. In addition, the site of binding by TEA to the α1- AR is at the conserved aspartic acid residue in transmembrane domain three, which is part of the constraining salt bridge. These results indicate a direct interaction of TEA in the receptor agonist binding pocket that leads to a disruption of the constraining salt bridge, thereby initiating α1-AR activation.</p

Regulation of the cellular localization and signaling properties of the α(1B)- and α(1D)-adrenoceptors by agonists and inverse agonists

The regulation of the cellular distribution and intracellular signaling properties of the α(1B)- and α(1D)- adrenoceptor (α1-AR) subtypes was examined in stably transfected Rat 1 fibroblasts. In unstimulated cells, α(1B)-AR expression was noted primarily on the cell surface. Treatment with phenylephrine induced internalization of the α(1B)-AR and promoted association with arrestin 2. The internalized α(1B)-AR colocalized with the transferrin receptor, an endosomal marker. In unstimulated fibroblasts, the α(1D)-AR was detected in a perinuclear orientation and was colocalized with arrestin 2 in a compartment also containing the transferrin receptor. After treatment with prazosin, which exhibits inverse agonist properties, the α(1D)-AR was redistributed from intracellular sites to the cellular periphery and was no longer associated with the transferrin receptor or arrestin 2. α(1D)-AR-expressing cells exhibited a high degree of basal activity for both inositol phosphate formation and extracellular signal regulated kinase (ERK), which was reduced by treatment with prazosin. In these cells, phenylephrine induced a dose-dependent increase in inositol phosphate formation but had no effect on ERK activity. In α(1B) -AR- expressing cells, phenylephrine stimulated both inositol phosphate formation and ERK activity. These data show that: 1) there are differences in the cellular localization of the α1-AR subtypes; 2) the α(1B)-AR exhibits expected G protein-coupled receptor activity regarding cellular localization, agonist-mediated internalization, and coupling to second messengers; and 3) the α(1D)-AR is constitutively active and, as a result, is localized to intracellular compartments involved in receptor recycling.</p