Peter Kotsonis

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Myogenic constriction describes the innate ability of resistance arteries to constrict in response to elevations in intraluminal pressure and is a fundamental determinant of peripheral resistance and, hence, organ perfusion and systemic blood pressure. However, the receptor/cell-type that senses changes in pressure on the blood vessel wall and the pathway(More)
Endothelial nitric-oxide synthase (NOS-III) is defined as being strictly dependent on Ca(2+)/calmodulin (CaM) for activity, although NO release from endothelial cells has been reported to also occur at intracellular free Ca(2+) levels that are substimulatory for the purified enzyme. We demonstrate here that NOS-III, but neither NOS-I nor -II, is rapidly and(More)
Soluble guanylyl cyclase (sGC) is an important effector for nitric oxide (NO). It acts by increasing intracellular cyclic GMP (cGMP) levels to mediate numerous biological functions. Recently, 1H-[1,2, 4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ) was identified as a novel and selective inhibitor of this enzyme. Therefore, ODQ may represent an important(More)
We have cloned a guinea pig Vanilloid receptor 1 (VR1) from a dorsal root ganglion cDNA library and expressed it in CHO cells. The receptor has been functionally characterized by measuring changes in intracellular calcium produced by capsaicin, low pH and noxious heat. Capsaicin produced a concentration-dependent increase in intracellular calcium in guinea(More)
The biosynthesis of nitric oxide (NO) is catalyzed by homodimeric NO synthases (NOS). For unknown reasons, all NOS co-purify with substoichiometric amounts of (6R)-5,6,7,8-tetrahydrobiopterin (H(4)Bip) and require additional H(4)Bip for maximal activity. We examined the effects of H(4)Bip and pterin-derived inhibitors (anti-pterins) on purified neuronal(More)
 Feulgen/DNA cytophotometric determinations carried out in the root meristem of seedlings showed that substantial quantitative alterations in the nuclear genome are present between and within 15 natural populations of Dasypyrum villosum in Italy. When the most variant values are considered, there is a 17.6% difference between the mean genome size of the(More)
We investigated the coupling of the fMLP (N -formyl-L-methionyl-L-leucyl-L-phenylalanine; 'chemotactic peptide') receptor with phosphorylation of the actin-binding protein L-plastin in neutrophils. Using two-dimensional IEF (isoelectric focusing)/PAGE and MALDI-TOF (matrix-assisted laser desorption ionization-time-of-flight)-MS, L-plastin was identified as(More)
The underlying mechanisms regulating the activity of the family of homodimeric nitric oxide synthases (NOSs) and, in particular, the requirement for (6R)-5,6,7,8-tetrahydro-L-biopterin (H(4)Bip) are not fully understood. Here we have investigated possible allosteric and stabilizing effects of H(4)Bip on neuronal NOS (NOS-I) during the conversion of(More)
The family of nitric oxide synthases (NOS) catalyzes the conversion of L-arginine to L-citrulline and nitric oxide (NO), an important cellular messenger molecule which has been implicated in the pathophysiology of septic shock and inflammatory and neurodegenerative disease states. NOS can be maximally activated by the ubiquitous cofactor,(More)
Nitric oxide synthases (NOS) are homodimeric enzymes that NADPH-dependently convert L-arginine to nitric oxide and L-citrulline. Interestingly, all NOS also require (6R)-5,6,7, 8-tetrahydro-L-biopterin (H4Bip) for maximal activity although the mechanism is not fully understood. Basal NOS activity, i.e. that in the absence of exogenous H4Bip, has been(More)