How calcium signals in myocytes and pericytes are integrated across in situ microvascular networks and control microvascular tone.
Bottom Line: Ca2+ signals vary between distributing arcade and downstream transverse and precapillary arterioles, are modified by agonists, with sympathetic agonists being ineffective beyond transverse arterioles.Increases of Ca2+ in pericytes and myocytes constrict all vessels except capillaries.These data reveal the structural and signalling specializations allowing blood flow to be regulated by myocytes and pericytes.
Affiliation: Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, L69 3BX, UK.Show MeSH
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Mentions: The aim of experiments such as that illustrated in Fig. 4 was to investigate whether the observed calcium signals were sufficient to close or constrict the vessels or produce vasomotion (Supplementary Movie 6). Fig. 4B shows that low frequency (<0.05 Hz) Ca2+ oscillations induced by a low concentration of PE (1 μM) resulted in only uncoordinated transient twitching of individual myocytes associated with local vasomotion. Similar results were seen with low concentrations of AVP and ET-1 throughout the arteriolar network. We found that the functional impact of single cell contraction depended upon the diameter of the microvessel and was maximal in the smallest vessels; thus in the precapillary arterioles contraction of one cell was sufficient to produce occlusion (Fig. 4C, black bar), but this was not the case in larger diameter vessels. Increasing the agonist concentration increased the frequency of oscillations (Fig. 4B and C) and thence constriction. The higher frequency of Ca2+ oscillations in the myocytes of transverse and precapillary arterioles induced a substantially greater arteriolar constriction (Fig. 4C; Supplementary Movie 6).
Affiliation: Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, L69 3BX, UK.