I

Calmodulin

cGMP 〉 cAMP

Heart, brain, kidney, liver, skeletal muscle, smooth muscle

Vinpocetine

Phenothiazines

II

cGMP, cAMP

Adrenal cortex, brain, corpus cavernosum, heart, liver, kidney, airway smooth muscle, platelets

ENHA

III

cAMP〉cGMP

Heart, corpus cavernosum, platelets, smooth muscle, liver, kidney, inflammatory cells (T&B lymphocytes, basophils, mast cells, monocytes, macrophages)

Amrinone

Cilostamide

Cilostazol

Imadazodan

Milrinone

Motapizone

Olprinone

Pimobendam

Piroximone

IV

cAMP

Kidney, lung, heart, skeletal muscle, smooth muscle (vascular, visceral, airway), platelets, inflammatory cells (T&B lymphocytes, basophils, mast cells, monocytes, macrophages, endothelial cells, eosinophils, neutrophils)

Enoximone

Rolipram

III & IV

cAMP, CGMP

As above

Benafentrine

Piclmilast

Tibenelast

Tolafentrine

Zardavarine

VII

cAMP

Skeletal muscle, heart, kidney, airways, T&B lymphocytes, monocytes, eosinophils

Dipyridamole

Nonspecific

cAMP, adenosine

Caffeine

Papaverine

Theophylline