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. 2023 Jan 23;43(7):1142–1152. doi: 10.1177/0271678X231152549

Figure 2.

Figure 2.

Noradrenaline (NA) contracts capillary pericytes without raising pericyte [Ca2+]i in acute rodent cerebral cortical slices. (a) Capillary diameter or somatic [Ca2+]i was measured in acute cortical slices using two-photon (2-p) or differential interference contrast (DIC) imaging to capture the onset of the NA-evoked contraction (DIC images acquired every 5–30 sec and 2-p stacks every 10 sec). (b) DIC image of rat cortical capillary with pericyte (white arrow) before and after stimulation with 200 µM noradrenaline (NA). The lumen diameter was measured at the pericyte soma as indicated by the red line. (c) Left: Exemplar time course of Continued.NA-evoked capillary constriction measured at the pericyte soma in response to aCSF containing 0, 2 or 200 µM NA. Right: Mean capillary constriction after 15 mins (n = 5 in aCSF from 3 rats; n = 9 for 2 µM NA from 9 rats; n = 6 for 200 µM NA from 3 rats). (d) Two-photon images of penetrating arteriole (PA) smooth muscle cells (SMCs) and 1st order capillary pericyte expressing GCaMP5g and tdTomato in NG2-CreERT2-GCaMP5g mice. (e) Left: time course of mouse pericyte [Ca2+]i in response to NA in the presence or absence of TTX. Right: NA does not raise pericyte [Ca2+]i in the presence or absence of TTX (n = 6 pericytes for NA from 3 mice; n = 5 pericytes for NA+TTX from 3 mice). (f) After 10 min of pre-incubation with NA (not shown), application of the Gq-coupled agonist endothelin-1 (ET-1) in the continuous presence of NA raises mouse pericyte [Ca2+]i as compared to continuous NA application alone (slow decline of fluorescence may reflect bleaching; n = 9 pericytes for NA from 3 mice; n = 7 for NA+ET-1 from 3 mice). (g) NA does not raise mouse arteriolar smooth muscle cell (SMC) [Ca2+]i in the presence or absence of TTX (n = 3 for NA from 3 mice; n = 3 for NA+ET-1 from 3 mice). (h–i) The α1 agonist phenylephrine (1 µM) does not raise [Ca2+]i (h) in mouse cortical pericytes (n = 6 from 3 mice) or arteriolar SMCs (n = 5 from 3 mice) nor decrease capillary or arteriole diameter (i). (j) The 20-HETE synthesis inhibitor HET0016 (100 nM) had no significant effect on the NA-evoked capillary constriction at pericytes (n = 4 from 3 rats, data without HET0016 are replotted from panel c).