Fig 1.
Diagram depicting antagonistic regulatory effects on vasoconstriction and blood pressure due to loop interrelationships among AVP, ANP, and RAAS neuroendocrine systems.
Labels for functional agents are the following. ACO: adrenal cortex; ACR: aortic arc and carotid sinus stretch receptors; ASR: atrial stretch receptors; DTC: renal distal tubule and collecting duct; HMY: heart myocytes; JGC: juxtaglomerular cells; NTS: nucleus tractus solitarii; SFO: subfornical organ; SPN: supraoptic and paraventricular nuclei; VSM: vascular smooth muscle. Labels for effect mediators are the following. AVP: arginine vasopressin; ANP: atrial natriuretic peptide; ANGII: angiotensin II; CNS: central nervous system. Lines with arrow ending indicate activation; lines with butt ending indicate inhibition.
Fig 2.
The two coexisting feedback schemes: The Renal Distal Tubule and Collecting Duct regulation (left) and the Vascular Smooth Muscle regulation (right).
Fig 3.
Diagram depicting antagonistic regulatory effects on vasoconstriction consisting of AVP and ANP endocrine systems acting on crosstalking signal transduction pathways of VSM, and stretch receptors closing the loops.
Labels for functional agents are the following. AMI: actomyosin interaction; ANPR: atrial natriuretic peptide receptor; CaM: calmodulin; CPI-17: protein phosphatase 1 regulatory subunit 14A; GC: guanylate cyclase; GEF: guanine nucleotide exchange factor; Gq: Gq alpha subunits of heterotrimeric G proteins; G12/13: G12/G13 alpha subunits of heterotrimeric G proteins; IP3R: inositol trisphosphate receptor; MLC myosin light chain; MLCK: myosin light chain kinase; MLCP: myosin-light-chain phosphatase; PKG: cGMP-dependent protein kinase; PLC: phospholipase C; PMCA: plasmamembrane Ca2+-ATPase; RhoA: Ras homolog gene family member A small GTPase; ROCK: Rho-associated protein kinase; V1R vasopressin receptor 1. Labels for effect mediators and anatomical districts are the following. cGMP: cyclic guanosine monophosphate; IP3: inositol trisphosphate. Other labels and line endings as in Fig 1.
Fig 4.
Fig 5.
Function jωΘVSM + 1 + pejτ1ω + qejτ2ω plotted in the complex plane: Case with higher oscillation propensity (red), case with lower oscillation propensity (black).
The radius of the blue circle centered in the origin and tangent to the curve is inversely proportional to the oscillation propensity.
Fig 6.
The oscillation propensity J* for ΘVSM = 0.5 minutes as a function of the delays τ1 and τ2 in the range [2, 4] minutes, corresponding to p = 0.5 and q = 0.5 (top left), p = 0.4 and q = 0.6 (top right), p = 0.3 and q = 0.7 (bottom left), p = 0.2 and q = 0.8 (bottom right).
Fig 7.
The interaction graph in Fig 3 (left) and its modified version (right).
Pointed arrows represent activation arcs, while circle-head arrows represent inhibition arcs.