Role of cGMP in carbon monoxide-induced cerebral vasodilation in piglets

• Published in: American journal of physiology. Heart and circulatory physiology 2004-01, Vol.286 (1), p.H304-H309
• Main Authors: Koneru, Padmaja, Leffler, Charles W
• Format: Article
• Language: English
• Subjects: Animals; Arterioles - drug effects; Carbon Monoxide - pharmacology; Cerebrovascular Circulation - drug effects; Cyclic GMP - analogs & derivatives; Cyclic GMP - pharmacology; Cyclic GMP - physiology; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Glutamic Acid - pharmacology; Manganese Compounds - administration & dosage; Manganese Compounds - pharmacology; Nitric Oxide - pharmacology; Nitric Oxide Donors - pharmacology; Nitroarginine - pharmacology; Nitroprusside - pharmacology; Swine; Vasodilation - physiology; Vasodilator Agents - pharmacology
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00810.2003

Laboratory for Research in Neonatal Physiology, Departments of Physiology and Pediatrics/Obstetrics and Gynecology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 Submitted 22 August 2003 ; accepted in final form 8 September 2003 The hypothesis was addressed that CO-induced cerebral vasodilation requires a permissive cGMP signal that can be produced by nitric oxide (NO). Anesthetized piglets were implanted with cranial windows for measurement of pial arteriolar responses to stimuli. Pial arterioles dilated in response to isoproterenol (Iso), sodium nitroprusside (SNP), and CO or the CO-releasing molecule Mn 2 (CO) 10 [dimanganese decacarbonyl (DMDC)]. 1 H -[1,2,4]oxadiazolo[4,3- a ]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor, decreased cerebrospinal fluid (CSF) cGMP and selectively inhibited dilations to SNP and DMDC without affecting the dilation to Iso. However, DMDC did not cause an increase in cortical periarachnoid CSF cGMP concentration. cGMP clamp with a threshold dilator level of 8-bromo-cGMP (10 –4 M) and ODQ restored the dilation to DMDC that had been blocked by ODQ alone. Under these conditions, cGMP was present but could not increase. Inhibition of the pial arteriolar dilation to glutamate by N -nitro- L -arginine, which blocks NO synthase, was similar to that by heme oxygenase inhibitors, which block endogenous CO production. The dilation to glutamate, similar to dilation to DMDC, was partially restored by 8-bromo-cGMP and completely restored by SNP (5 x 10 –7 M). These data suggest that the permissive role of NO in CO- and glutamate-induced vasodilation involves maintaining the minimum necessary cellular level of cGMP to allow CO to cause dilation independently of increasing cGMP. carbon monoxide-releasing molecule; cranial window; cerebrovascular circulation; glutamate; nitric oxide Address for reprint requests and other correspondence: C. W. Leffler, Dept. of Physiology, Univ. of Tennessee, 894 Union Ave., Rm. 426, Memphis, TN 38163 (E-mail: cleffler{at}physiol.utmem.edu ).