Vasovagal syncope is a common clinical syndrome that has complex and variable mechanisms and is difficult to manage. Advancements are being made in laboratory investigations of its triggering mechanisms. Randomized, controlled trials of pharmacologic and nonpharmacologic interventions are needed. Mechanism-targeted therapeutic trials may improve clinical outcomes.

(1) A functional line of block is seen at the posteromedial (sinus venosa region) right atrium during counterclockwise and clockwise atrial flutter. (2) All lateral wall right atrial activation can be uniform during flutter, without linear block or double potentials in the region of the crista terminalis. (3) Activation at the site of posteromedial right atrial functional block can organize to subsequently initiate isthmus-dependent atrial flutter.

Cyclic ADP-ribose (cADPR) was shown to induce calcium release from the endoplasmic reticulum via ryanodine-sensitive pathways. In smooth muscle, two pathways for calcium release from the sarcoplasmic reticulum (SR) have been previously demonstrated: D-myo-inositol 1, 4, 5-trisphosphate-gated and ryanodine-gated. However, evidence for cADPR as a regulator for SR Ca2+ release in smooth muscle is lacking. We used permeabilized porcine coronary artery smooth muscle cells to directly examine the stimulation of SR Ca2+ release by cADPR. The results provide direct evidence that cADPR stimulates SR Ca2+ release and that this response is not inhibited by heparin, by depletion of the caffeine-sensitive Ca2+ pool, or by blockade or ryanodine receptors. These results indicate a novel mechanism for Ca2+ release from the SR of vascular smooth muscle.

Soluble, redox-active, organic materials hold promise as charge-storage species for flow batteries; however, their stability during extended operation remains a key challenge. While a number of spectroscopic and electrochemical techniques are currently used to probe these complex and often ill-defined decay pathways, each technique has limitations, including accessibility and direct evaluation of practical electrolytes without preparatory steps. Here, we use microelectrode voltammetry to directly observe nonaqueous flow battery electrolytes, simultaneously identifying the rate of charged materials decay (reversible material loss) and total material decay (irreversible material loss). We validate this technique using ferrocene as a stable model redox couple, examine and address sources of error, and finally, demonstrate its capability by assessing the decay of a well-studied and moderately-stable substituted dialkoxybenzene [2,5-di-tert-butyl-1,4-bis(2methoxyethoxy)benzene]. These results suggest that microelectrodes may have utility for rapid assessment of redox electrolyte state-of-charge and state-of-health, both in-operando and postmortem.

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