This causes an increase in coronary vasodilatation. The symptoms of platinosis may include asthma, dermatitis, dyspnea, conjunctival vasodilatation, and rhinopharyngitis. Hyperdynamic circulation, with peripheral vasodilatation from low systemic vascular resistance, leads to hypotension. This is opposite to carbon dioxide in tissues causing vasodilatation, especially in the brain. Substance P-induced vasodilatation is dependent on nitric oxide release. The role of vasodilatation of the extracranial arteries, in particular, is believed to be significant. Mannitol has several effects, including vasodilatation of renal vasculature, osmotic diuresis, and free-radical scavenging. The endothelium secretes soluble factors to regulate vasodilatation and to preserve homeostasis. Histamine also binds to H1 and H2 receptors of the conjunctival vasculature and causes vasodilatation.