Altered autonomic control in conscious transgenic rabbits with overexpressed cardiac Gsalpha.
Both enhanced sympathetic drive and altered autonomic control are involved in the pathogenesis of heart failure. The goal of the present study was to determine the extent to which chronically enhanced sympathetic drive, in the absence of heart failure, alters reflex autonomic control in conscious, transgenic (TG) rabbits with overexpressed cardiac Gsalpha. Nine TG rabbits and seven wild-type (WT) littermates were instrumented with a left ventricular (LV) pressure micromanometer and arterial catheters and studied in the conscious state. Compared with WT rabbits, LV function was enhanced in TG rabbits, as reflected by increased levels of LV dP/dt (5,600 +/- 413 vs. 3,933 +/- 161 mmHg/s). Baseline heart rate was also higher (P < 0.05) in conscious TG (247 +/- 10 beats/min) than in WT (207 +/- 10 beats/min) rabbits and was higher in TG after muscarinic blockade (281 +/- 9 vs. 259 +/- 8 beats/min) or combined beta-adrenergic receptor and muscarinic blockade (251 +/- 6 vs. 225 +/- 9 beats/min). Bradycardia was blunted (P < 0.05), whether induced by intravenous phenylephrine (arterial baroreflex), by cigarette smoke inhalation (nasopharyngeal reflex), or by veratrine administration (Bezold-Jarisch reflex). With veratrine administration, the bradycardia was enhanced in TG for any given decrease in arterial pressure. Thus the chronically enhanced sympathetic drive in TG rabbits with overexpressed cardiac Gsalpha resulted in enhanced LV function and heart rate and impaired reflex autonomic control. The impaired reflex control was generalized, not only affecting the high-pressure arterial baroreflex but also the low-pressure Bezold-Jarisch reflex and the nasopharyngeal reflex.
Nishizawa
Takao
T
Department of Cell Biology & Molecular Medicine, University of Medicine & Dentistry of New Jersey, New Jersey Medical School, 185 South Orange Ave., MSB G609, Newark, NJ 07103, USA.
Shen
You-Tang
YT
Rossi
Franco
F
Hong
Chull
C
Robbins
Jeffrey
J
Ishikawa
Yoshihiro
Y
Sadoshima
Junichi
J
Vatner
Dorothy E
DE
Vatner
Stephen F
SF
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000503:physiopathology; D017704:Baroreflex; D001794:Blood Pressure; D001919:Bradycardia / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D004558:Electric Stimulation; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics / Q000378:metabolism*; D006339:Heart Rate; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009206:Myocardium / Q000378:metabolism*; D010656:Phenylephrine; D011433:Propranolol / Q000494:pharmacology; D011817:Rabbits / Q000235:genetics; D012018:Reflex; D012906:Smoke / Q000009:adverse effects; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D014026:Nicotiana; D014630:Vagus Nerve / Q000503:physiopathology; D016277:Ventricular Function, Left; D014702:Veratrine
D000319:Adrenergic beta-Antagonists; D018727:Muscarinic Antagonists; D012906:Smoke; D010656:Phenylephrine; D001285:Atropine; D011433:Propranolol; D019205:GTP-Binding Protein alpha Subunits, Gs; D014702:Veratrine