Altered nitric oxide calcium responsiveness of aortic smooth muscle cells in spontaneously hypertensive rats depends on low expression of cyclic guanosine monophosphate-dependent protein kinase type I.

Abstract

OBJECTIVES:

The nitric oxide/cyclic guanosine monophosphate (GMP)/cyclic GMP-dependent protein kinase type I (cGKI) pathway has been extensively investigated in the spontaneously hypertensive rat (SHR) as a possible pathogenetic factor. Therefore, we investigated the role of nitric oxide/cGKI on intracellular calcium dynamics ([Ca2+]i) of aortic smooth muscle cells isolated from control normotensive Wistar Kyoto rats (WKY) and SHR.

METHODS:

Rat aortic smooth muscle cells (RASMCs) were obtained from 12 to 16-week-old WKY and SHR. [Ca2+]i dynamics were monitored by imaging analysis of fura-2-loaded RASMCs. cGKI mRNA and cGKI protein expression were evaluated by reverse transcription-PCR and western blot. Plasmids codifying for enhanced green fluorescent protein (EGFP) or cGKIalpha-EGFP were transfected on SHR RASMCs.

RESULTS:

Angiotensin II similarly increased [Ca2+]i in WKY and SHR RASMCs. In WKY RASMCs, S-nitroso-N-acetyl-DL-penicillamine (SNAP, 1-100 micromol/l) reduced the decay time of angiotensin II-induced [Ca2+]i transient. On the contrary, in SHR cells, SNAP was ineffective. Dibutyryl cyclic GMP (1-100 nmol/l), a membrane-permeable cyclic GMP analogue, behaved similarly to SNAP. In naive SHR RASMCs, cGKI mRNA and cGKI protein were low or absent. After transfection of a plasmid encoding for cGKIalpha-EGFP, the [Ca2+]i dynamic of SHR-transfected cells regained sensitivity to the nitric oxide/cyclic GMP pathway.

CONCLUSION:

The low expression of cGKI determines the lack of nitric oxide/cyclic GMP-dependent regulation on [Ca2+]i transient in SHR RASMCs. This alteration may contribute to the development of hypertension and explain suboptimal responses to nitroglycerin and other nitric oxide-releasing molecules in patients.

• Authors: Lorenzo Di Cesare Mannelli, Silvia Nistri, Luca Mazzetti, Daniele Bani, Robert Feil, Paola Failli
• Journal: Journal of hypertension (J Hypertens) Vol. 27 Issue 6 Pg. 1258-67 (Jun 2009) ISSN: 1473-5598 [Electronic] Netherlands
• PMID: 19307986 (Publication Type: Journal Article)

Chemical References

• DNA Primers
• Nitric Oxide Donors
• RNA, Messenger
• Recombinant Proteins
• enhanced green fluorescent protein
• Angiotensin II
• Green Fluorescent Proteins
• Nitric Oxide
• Dibutyryl Cyclic GMP
• S-Nitroso-N-Acetylpenicillamine
• Cyclic GMP-Dependent Protein Kinase Type I
• Cyclic GMP-Dependent Protein Kinases

Topics

• Angiotensin II (pharmacology)
• Animals
• Aorta, Thoracic (metabolism)
• Base Sequence
• Calcium Signaling (drug effects, physiology)
• Cyclic GMP-Dependent Protein Kinase Type I
• Cyclic GMP-Dependent Protein Kinases (genetics, metabolism)
• DNA Primers (genetics)
• Dibutyryl Cyclic GMP (pharmacology)
• Green Fluorescent Proteins (genetics)
• Hypertension (genetics, metabolism)
• In Vitro Techniques
• Myocytes, Smooth Muscle (drug effects, metabolism)
• Nitric Oxide (metabolism)
• Nitric Oxide Donors (pharmacology)
• RNA, Messenger (genetics, metabolism)
• Rats
• Rats, Inbred SHR
• Rats, Inbred WKY
• Recombinant Proteins (genetics)
• S-Nitroso-N-Acetylpenicillamine (pharmacology)
• Transfection