Table 3.

Cell membrane permeability and activation constants for selected cyclic nucleotide analogs

Analog	cNMP conc. inside platelets (% of external)	cNMP conc. inside CHO cells (% of external)	Lipophilicitya log K w	Activationb PKG Iβ K a (μM)	Activationb PKA II K a (μM)
cGMP			0.77	0.9
2′-dcGMP (17)	0.5 ± 0.1	0.3 ± 0.5	0.66	21
8-Br-cGMP (15)	12.1 ± 3.5	13.5 ± 11.5	1.17	1.0
8-pCPT-cGMP (16)	19.6 ± 4.7	n/d	2.52	0.9
8-Br-PET-cGMP (22)	30.9 ± 5.7	24.1 ± 9.7	2.83	0.009
cAMP			1.09		0.08
2′-dcAMP (6)	0.2 ± 0.3	0.1 ± 0.2	0.97		n/d
8-Br-cAMP (4)	n/d	n/d	1.35		0.09
Sp-5,6-DCl-cBIMPS (11)	n/d	n/d	2.99		0.12

All experiments were performed three times

n/d not determined

^aKrass et al. (1997)

^bPoppe et al. (2008)