Figure 5.

Effects of Gβ5 knockout on cholinergic stimulation of pancreatic islets and pupillary constrictor muscle. A) Islets from wild-type (control) and Gnb5^−/− mice were loaded with fura-2. The series of 13 traces show raw data from selected regions of interest within a representative control islet. The islet was perifused with 3 mM glucose (3G) to establish a baseline, then challenged with 100 μM Oxo-M in 3G, followed up by 100 μM Oxo-M in 16 mM (high) glucose (16G) for 10 min. It was then perifused with 3G for 20 min (gap in the traces) and challenged again with 16G for 10 min. Oscillations of free Ca²⁺ occurred only in the presence of Oxo-M. B) Ca²⁺ oscillations in wild-type and Gnb5^−/− islets. The data show an average of >10 areas of interest selected within 1 islet of each genotype. C) Changes in [Ca²⁺]_i induced by Oxo-M in 3G. Each dot represents the response of 1 islet (region of interest placed around the whole islet). D) Average amplitude of Ca²⁺ oscillations induced by Oxo-M in 16G. E) Frequency of Ca²⁺ oscillations induced by Oxo-M in 16G quantified as the number of peaks per minute. C–E) Each dot represents 1 islet (3–4 mice per genotype). F) Enucleated eyes from WT and Gnb5^−/− (KO) mice were incubated in HBSS and photographed 60 min after addition of 1 mM pilocarpine. G) Time-course of pilocarpine-induced pupil constriction recorded in eyes from control and Gnb5^−/− mice. After stimulation, images were taken at the indicated times, and pupil diameter was measured. Data points are means ± sd from 6 independent experiments on eyes from 3 individual animals of each genotype. H) In situ RNA hybridization of a mouse eye section using probes for mRNAs encoding Gβ5 (Gnb5) and M3R (Chrm3). A representative image shows the sphincter smooth muscle, iris, lens, and lens epithelium (LE).