A Vibrating Ca2+-selective Electrode Measures Ca2+ Flux Induced by the Neuropeptide FMRFamide in a Gastropod Ventricle

5-Hydroxytryptamine Stimulates Net Ca2+Flux in the Ventricular Muscle of a Mollusc (Busycon canaliculatum) During Cardioexcitation

“…The data are means pooled from three experiments on three ventricles Ϯ SD. reduces the FMRFamide response by 60% in the same preparation (Devlin, 1997). Therefore, 5-HT relies less on extracellular Ca 2ϩ ions than does FMRFamide during the process of E-C coupling in the Busycon ventricle.…”

“…To determine if the net efflux was in part due to activity of the Na ϩ -Ca 2ϩ exchanger, a Na ϩ -free, Li ϩ -substituted saline (Li ϩ ASW) was used. The Li ϩ ASW reduces the basal net Ca 2ϩ efflux during normal, autorhythmic activity of the Busycon trabeculae by only 20%-30%, whereas the 5-HT and FMRFamide responses are inhibited during Li ϩ treatment by 40% and 73%, respectively (Devlin, 1997). This difference in response suggests a greater reliance on the Na ϩ -Ca 2ϩ exchanger during chemically mediated excitation than during spontaneous myogenic activity.…”

“…The present study uses a newer technique to study Ca 2ϩ flux, noninvasive self-referencing Ca 2ϩ electrodes, to determine possible mechanisms by which 5-HT affects trans-sarcolemmal net Ca 2ϩ flux in the Busycon ventricle as a clue to understanding its role during the excitation-contraction (E-C) coupling in the gastropod heart. An earlier study focused on the action of FMRFamide on net Ca 2ϩ flux in the ventricle of Busycon canaliculatum (Devlin, 1997), so we may be able to compare mechanisms working at putative Ca 2ϩ pools accessed by 5-HT and FMRFamide to achieve the same end-enhanced cardiac performance.…”

Self-referencing, non-invasive, ion selective electrode for single cell detection of trans-plasma membrane calcium flux

“…As discussed in the text, this undershoot is relatively constant from electrode to electrode and probably represents delays in the response time. Knox et al, 1996;Devlin and Smith, 1996;Devlin, 1997;HoldawayClarke et al, 1997;Messerli et al, 1999). In the study of Yamoah et al (1998) using the calcium-selective Seris probe, flux measurements were made from hair cell stereocilia, with resting net influx at the hair tip, as expected from other electrophysiological work.…”

“…In the studies of Leah Devlin (Devlin, 1997;Devlin and Smith, 1996;Devlin and Schlosser, 1999) calcium efflux from smooth muscle of the holothurian, Sclerodactyla briareus, were reliably measured in response to neurotransmitters and hormones. (Sclerodactyla briareus is a Sea Cucumber, which as the name implies is not noted for doing anything in a hurry).…”