Mauban JRH, Zacharia J, Zhang J, Wier WG. Vascular tone and Ca(2+) signaling in murine cremaster muscle arterioles in vivo.
Microcirculation 2013;
20:269-77. [PMID:
23140521 DOI:
10.1111/micc.12025]
[Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 11/02/2012] [Indexed: 12/12/2022]
Abstract
OBJECTIVES
We sought to determine some of the molecular requirements for basal state "tone" of skeletal muscle arterioles in vivo, and whether asynchronous Ca(2+) waves are involved or not.
METHODS
Cremaster muscles of anesthetized exMLCK and smGCaMP2 biosensor mice were exteriorized, and the fluorescent arterioles were visualized with wide-field, confocal or multiphoton microscopy to observe Ca(2+) signaling and arteriolar diameter.
RESULTS
Basal state tone of the arterioles was ~50%. Local block of Ang-II receptors (AT1 ) or α1 -adrenoceptors (α1 -AR) had no effect on diameter, nor did complete block of sympathetic nerve activity (SNA). Inhibition of phospholipase C caused dilation nearly to the Ca(2+) -free (passive) diameter, as did exposure to nifedipine or 2-APB. Arterioles were also dilated when treated with SKF96365. High-resolution imaging of exMLCK fluorescence (ratio) or GCaMP2 fluorescence in smooth muscle cells failed to reveal Ca(2+) waves (although Ca(2+) waves/transients were readily detected by both biosensors in small arteries, ex vivo).
CONCLUSIONS
Arterioles of cremaster muscle have vascular tone of ~ 50%, which is not due to α1 -AR, AT1 R, or SNA. PLC activity, L-type Ca(2+) channels, 2-APB- and SKF96365-sensitive channels are required. Propagating Ca(2+) waves are not present. A key role for PLC and InsP3 R in vascular tone in vivo, other than producing Ca(2+) waves, is suggested.
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