Heart-Microcirculation Connection Effects of ANP (Atrial Natriuretic Peptide) on Pericytes Participate in the Acute and Chronic Regulation of Arterial Blood Pressure
Authors: Spiranec Spes, Katarina; Chen, Wen; Krebes, Lisa; Voelker, Katharina; Abesser, Marco; Eder Negrin, Petra; Cellini, Antonella; Nickel, Alexander; Nikolaev, Viacheslav O.; Hofmann, Franz; Schuh, Kai; Schweda, Frank; Kuhn, Michaela
Cardiac ANP (atrial natriuretic peptide) moderates arterial blood pressure. The mechanisms mediating its hypotensive effects are complex and involve inhibition of the renin-angiotensin-aldosterone system, increased natriuresis, endothelial permeability, and vasodilatation. The contribution of the direct vasodilating effects of ANP to blood pressure homeostasis is controversial because variable levels of the ANP receptor, GC-A (guanylyl cyclase-A), are expressed among vascular beds. Here, we show that ANP stimulates GC-A/cyclic GMP signaling in cultured microvascular pericytes and thereby the phosphorylation of the regulatory subunit of myosin phosphatase 1 by cGMP-dependent protein kinase I. Moreover, ANP prevents the calcium and contractile responses of pericytes to endothelin-1 as well as microvascular constrictions. In mice with conditional inactivation (knock-out) of GC-A in microcirculatory pericytes, such vasodilating effects of ANP on precapillary arterioles and capillaries were fully abolished. Concordantly, these mice have increased blood pressure despite preserved renal excretory function. Furthermore, acute intravascular volume expansion, which caused release of cardiac ANP, did not affect blood pressure of control mice but provoked hypertensive reactions in pericyte GC-A knock-out littermates. We conclude that GC-A/cGMP-dependent modulation of pericytes and microcirculatory tone contributes to the acute and chronic moderation of arterial blood pressure by ANP. Graphic Abstract Ais available for this article.
Phytol, (E)-nerolidol and spathulenol from Stevia rebaudiana leaf essential oil as effective and eco-friendly botanical insecticides against Metopolophium dirhodum
INDUSTRIAL CROPS AND PRODUCTS
Authors: Benelli, Giovanni; Pavela, Roman; Drenaggi, Ettore; Desneux, Nicolas; Maggi, Filippo
Stevia rebaudiana (Asteraceae) is a medicinal plant of economic importance in the food market for the manufacture of natural sweeteners, namely steviol glycosides. The plant biomass used on an industrial level may also be the source of an essential oil (EO) of potential interest for developing novel insecticides. Here, the leaf EO chemical composition of S. rebaudiana growing in central Italy was analysed by gas chromatography-mass spectrometry (GC-MS). The EO insecticidal efficacy was evaluated against the aphid Metopolophium dirhodum (Hemiptera: Aphididae), a major pest of cereals. The EO composition was dominated by sesquiterpenes, i.e. caryophyllene oxide (20.7 %), spathulenol (14.9 %) and (E)-nerolidol (8.0 %), and diterpenes, i.e. phytol (9.2 %). The EO was effective against M. dirhodum aphids, showing an LC 50(90) of 5.1 and 10.8 mL L-1, respectively. The efficacy of the EO major constituents, namely caryophyllene oxide, spathulenol, (E)-nerolidol and phytol was also tested against M. dirhodum. Phytol was the most effective aphicide (LC50(90) = 1.4(4.2) mL L-1), followed by (E)-nerolidol (LC50(90) = 3.5(9.3) mL L-1) and spathulenol (LC50(90) = 4.3(7.5) mL L-1). The EO was minimally toxic towards non-target Eisenia fetida adults and Harmonia axyridis larvae and adults. Overall, phytol, (E)-nerolidol and spathulenol can be considered further for developing effective and eco-friendly green insecticides against aphids.