Rod-type cyclic nucleotide-gated cation channel is expressed in vascular endothelium and vascular smooth muscle cells

Objectives: Ca++-permeable nonselective cation channels mediate the entry o f extracellular Ca++ in vascular endothelium. They are also partly responsi ble for Ca++ entry in vascular smooth muscle cells (SMCs). The molecular id entities of these channels have not been identified. The aim of this study is to examine whether rod-type nucleotide-gated nonselective cation (CNG1) channel, a channel which has been molecularly cloned, is related to the non selective channels in vascular cells. Methods: We used RT-PCR, molecular cl oning, northern Blot and in situ hybridization to examine the expression of CNG1 mRNA in a variety of guinea Dig and rat blood vessels with different diameters and in cultured vascular endothelial cells and vascular smooth mu scle cells. Results: We have cloned a 402-bp partial cDNA of CNG1 channel f rom guinea pig mesenteric arteries. RT-PCR and southern blot results indica te that the CNG1 mRNA is expressed in both cultured vascular endothelial an d cultured vascular SMCs. Northern blot revealed the transcripts of similar to 3.2 kb, similar to 5.0 kb, and similar to 1.8 kb in cultured endothelia l cells. In situ hybridization yielded strong labeling in endothelium layer of aorta, medium-sized mesenteric arteries, and small mesenteric arteries. Conclusion: Our findings suggest a potential role of CNG protein for Ca+entry in vascular endothelium and vascular smooth muscles. The high express ion of CNG1 mRNA in the endothelium of medium-sized arteries and small-size d arteries implicates a possible involvement of CNG1 protein in the regulat ion of blood supply to different regions and in the regulation of arterial blood pressure. (C) 1999 Elsevier Science B.V. All rights reserved.