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: In contrast to the data from smooth muscle cells, the responses seen in pericytes did not depend on location (n = 11–28). Thus increases of Ca2+ to AVP and ET-1 were seen at all locations but no pericytes in any vessel responded to PE or caffeine (Fig. 3A and B; Table 1; Supplementary Movie 5). Pericytes responded in an agonist specific manner to AVP and ET-1 (Fig. 3B). At low concentrations (1 nM), AVP produced either no response or elicited a single Ca2+ oscillation in all sections of pericytic microvessels (Table 1). At higher concentrations of AVP (5 nM) the signal changed from one oscillation to several in most pericytes throughout the network (Fig. 3E), with frequencies of 0.02–0.03 Hz (n = 18). In contrast to AVP, in all pericytes, ET-1 (1–5 nM) caused a single Ca2+ transient which decayed very slowly (Fig. 3B–E). Examination of Figs. 2 and 3 shows that there are obvious differences between the characteristics of the Ca2+ signals in myocytes and pericytes. Next we wished to investigate if these patterns of Ca2+ oscillations, which varied between vessels, led to differing functional responses in the microcirculatory vessels.
Affiliation: Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, L69 3BX, UK.