Abnormalities in the metabolism of cyclic nucleotides have been observed in human as well as in experimental hypertension. This study, conducted in spontaneously hypertensive rats (SHR), established that abnormalities of cyclic nucleotides may be observed in platelets, an easily obtainable tissue which possesses features in common with vascular smooth muscle. Basal levels of cyclic AMP and cycl...

The discovery of cyclic nucleotides as second messengers has paved the way to much of what we know about signal transduction and the mechanisms of hormone action. Even though other signaling pathways activated by growth factors are the focus of much attention, cyclic nucleotides remain among the most important players in hormone action. When envisioned as a linear cascade, the steps involved in...

Phagocytosis of isolated outer segments by cultured rat pigment epithelium was decreased by cyclic 3',5'adenosine monophosphate (cyclic AMP), dibutyryl cyclic AMP, and three phosphodiesterase inhibitors (isobutylmethylxanthine, papaverine, and SQ 65442). Cyclic GMP and its dibutyryl derivative had little effect on phagocytosis. Phagocytosis was moderately reduced by several other purine nucleot...

Cyclic nucleotide-sensitive ion channels, known as HCN and CNG channels, are crucial in neuronal excitability and signal transduction of sensory cells. HCN and CNG channels are activated by binding of cyclic nucleotides to their intracellular cyclic nucleotide-binding domain (CNBD). However, the mechanism by which the binding of cyclic nucleotides opens these channels is not well understood. He...