Table 2.

Effects of pertussis toxin and Ca²⁺ channel blockers on glucagon secretion

		Glucagon secretion (pg islet−1 h−1)
Line	Experimental condition	1 mm glucose	20 mm glucose
1	—	30.7 ± 1.2 (8)	19.8 ± 1.8 (10)*
2	20 μm nifedipine	27.9 ± 1.4 (8)	21.4 ± 2.1 (10)**
3	100 nmω-conotoxin GVIA	18.1 ± 2.2 (8)†	16.7 ± 1.4 (10)
4	Overnight culture	24.2 ± 2.4 (10)	10.1 ± 0.60 (10)*
5	Overnight pretreatment with 100 ng ml−1 pertussis toxin	55.0 ± 7.0 (10)‡	22.7 ± 2.4 (12)*,‡

Data are mean values ±s.e.m. of indicated number of experiments (n).

^*P < 0.005 versus 1 mm glucose under same experimental conditions (comparison within same line);

^**P < 0.05 versus 1 mm glucose + nifedipine (same line);

^†P < 0.005 versus 1 mm glucose (line 1);

^‡P < 0.001 versus release measured in islets cultured overnight but not exposed to pertussis toxin.