title: Synthetic salusins as cardiac depressors in rat.
abstract: Using bioinformatic analyses of full-length, enriched human cDNA libraries, we recently identified salusins, multifunctional related peptides ubiquitously expressed in major human tissues. Salusins cause transient and profound hypotension when injected intravenously to rats, the hypotensive effect of salusin-beta being especially striking. However, the mechanisms of this hypotensive action remain elusive. To determine whether salusins modulate cardiac function in rats, we studied serial changes of systemic hemodynamics and functions of isolated perfused working and nonworking hearts before and after salusin administration. Intravenous salusin-beta administration to intact anesthetized rats caused a temporary rapid, profound decrease in aortic blood flow concomitantly with hypotension and bradycardia without affecting systemic vascular resistance. Salusin-beta-induced hypotension and bradycardia were completely blocked by pretreatment with atropine, a muscarinic receptor antagonist, but not by propranolol. In isolated perfused working rat hearts, salusin-beta significantly decreased cardiac output, aortic flow, and stroke work. However, it did not affect coronary flow in isolated working and nonworking hearts. Our results indicate that salusins induce potent hypotension via negative inotropic and chronotropic actions. Salusin-beta promotes its actions by facilitating vagal outflows to the heart, whereas the negative inotropism of salusin-beta is also mediated via a direct myotropic effect.
authors.affiliation: Tokyo Medical and Dental University Medical Hospital, Tokyo, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Izumiyama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tanaka
authors.forename: Koso
authors.initials: K
authors.lastname: Egi
authors.forename: Makoto
authors.initials: M
authors.lastname: Sunamori
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hirata
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Shichiri
mesh_terms: D000251:Adenosine Triphosphatases / Q000138:chemical synthesis / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000502:physiology; D001919:Bradycardia / Q000139:chemically induced; D002302:Cardiac Output / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D006801:Humans; D007022:Hypotension / Q000139:chemically induced; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D013318:Stroke Volume / Q000187:drug effects
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; C478739:TOR2A protein, human; D000251:Adenosine Triphosphatases