Data from: A four-component model of the action potential in mouse detrusor smooth muscle cell

Detrusor smooth muscle cells (DSMCs) of the urinary bladder are
electrically connected to one another via gap junctions and form a three
dimensional syncytium. DSMCs exhibit spontaneous electrical activity,
including passive depolarizations and action potentials. The shapes of
spontaneous action potentials (sAPs) observed from a single DSM cell can
vary widely. The biophysical origins of this variability, and the precise
components which contribute to the complex shapes observed are not known.
To address these questions, the basic components which constitute the sAPs
were investigated. We hypothesized that linear combinations of scaled
versions of these basic components can produce sAP shapes observed in the
syncytium. The basic components were identified as spontaneous evoked
junction potentials (sEJP), native AP (nAP), slow after hyperpolarization
(sAHP) and very slow after hyperpolarization (vsAHP). The experimental
recordings were grouped into two sets: a training data set and a testing
data set. A training set was used to estimate the components, and a test
set to evaluate the efficiency of the estimated components. We found that
a linear combination of the identified components when appropriately
amplified and time shifted replicated various AP shapes to a high degree
of similarity, as quantified by the root mean square error (RMSE) measure.
We conclude that the four basic components - sEJP, nAP, sAHP, and vsAHP -
identified and isolated in this work are necessary and sufficient to
replicate all varieties of the sAPs recorded experimentally in DSMCs. This
model has the potential to generate testable hypotheses that can help
identify the physiological processes underlying various features of the
sAPs. Further, this model also provides a means to classify the sAPs into
various shape classes.