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. 2023 Sep 20;44(2):155–168. doi: 10.1177/0271678X231201241

Figure 2.

Figure 2.

Responses of penetrating arterioles, neurons, and neurovascular coupling to whisker stimulation during euglycemia and hypoglycemia. (a) Basal arteriole diameter during insulin-induced hypoglycemia. Data points (black circles) represent individual arteriole diameter measurements. Data are normalized to the mean of all arteriole diameter measurements during euglycemia for each experiment. Colored rectangles at the bottom indicate glycemic ranges [color scale the same as in (b)]. Combined data from 8 vessels in 8 mice, 15 experiments. Inset: red line plots the diameter vs glycemic level for a single experiment on a single arteriole. Axes are the same as the main figure. (b) Summary of the results in (a), with data binned into 4 glycemic ranges (euglycemia, 70–150; mild hypoglycemia, 54–70; moderate hypoglycemia, 35–54; and severe hypoglycemia, 20–35 mg/dL). Data for trials where blood glucose was >150 mg/dL were omitted. Individual measurements, mean ± SD, n = 8 vessels in 8 mice, 15 experiments; *, p < 0.05; ***, p < 0.001; n.s. not significant. (c) Basal arteriole diameter during hypoglycemia (20 to 44 mg/dL) with data normalized to the mean diameters during euglycemia (70–150 mg/dL). Responses of 9 arterioles are shown. Individual measurements, mean ± SD, n = 9 vessels, 9 mice. 20 of the 36 pairwise comparisons between vessels are significantly different. (d) Summary of responses to whisker stimulation. For each experiment, responses are normalized to the mean of the responses during euglycemia. Neuronal responses represent the peak change in the amplitude of GCaMP6s fluorescence in neuronal processes. Arteriole responses represent the peak change in the arteriole diameter. NVC (arteriole/neuron) represents a measure of neurovascular coupling as calculated by the ratio of the arteriole response to the neuronal response for each stimulus trial. NVC (kernel) represents a measure of neurovascular coupling, as calculated by the peak amplitude of the convolution kernel relating the neuronal response to the vessel response, calculated for each stimulus trial. Outliers were removed for panel (d) calculations (see Methods). None of the responses measured during hypoglycemia are significantly different from the euglycemia or control responses. Mean ± SD, n = 9 vessels in 9 mice.