Table 1.

Effect of ionomycin, 4β-PMA, 4α-PDD, and forskolin on volume of C11-MDCK cells

Additions, μM	n	Cell Volume, %
None (control)	3	97 ± 5
Ionomycin, 1	4	70 ± 4 (P < 0.01)
4β-PMA, 1	4	73 ± 4 (P < 0.05)
4α-PDD, 1	3	105 ± 8 (NS)
Forskolin, 10	3	103 ± 7 (NS)
Ionomycin + 4β-PMA	4	43 ± 6 (P < 0.002)

Means ± SE in n experiments and P values are shown. Cells were incubated for 1 h in medium A with compounds listed in the left column. Initial cell volume was taken as 100%. MDCK, Madin-Darby canine kidney; 4β-PMA, 4β-phorbol 12-myristate 13-acetate; 4α-PDD, 4α-phorbol-12,13-didecanoate; NS, not significant.