Figure 1.

Classification of β-cell sub-membrane Ca²⁺ responses to elevation in glucose as recorded with TIRF. Responses to 16.5 mM glucose at 37° C in mouse primary pancreatic β-cells. n = 239. Responses from 1,017 cells were analysed overall. Percentages are of 239 control cells of male WT mice of one genetic background to exclude potential genetic- or sex differences in response type distribution. Approximately 96% showed a prominent global calcium response. In 116 cells, 16.5 mM glucose evoked a mean peak height of 2.4 ± 0.01 ΔF/F₀. (a) The most common response (type 1, ca. 60% of responses) resembles the standardized triphasic response. (b) The slow Ca²⁺ oscillations classified as type 2 often occurred at periods of ca. 5 min. (c) Response type 3 consists of numbers of large transients superimposed on a slow increase in Ca²⁺. These responses were rare (ca. 2%). (d) Type 4 responses (ca. 25%) resemble the triphasic response, but with a less steep Ca²⁺ rise. (e) A very small number of cells did not respond to glucose (ca. 2%).