title: Renal sympathetic and circulatory responses to activation of the exercise pressor reflex in rats.
abstract: We investigated the role played by the exercise pressor reflex in sympathetic regulation of the renal circulation in rats. In mid-collicular decerebrate rats, mean arterial pressure (MAP), heart rate (HR), left renal cortical blood flow (RCBF) and left renal sympathetic nerve activity (RSNA) were recorded before and during 30 s of static contraction of the left triceps surae muscles evoked by electrical stimulation of the tibial nerve, which activates both metabo- and mechanosensitive muscle afferents, and during 30 s of passive stretch of the left Achilles tendon, which selectively activates mechanosensitive muscle afferents. Static contraction (n = 17, +344 +/- 34 g developed tension) significantly (P < 0.05) increased MAP (+14 +/- 3 mmHg), HR (+6 +/- 1 beats min(-1)) and RSNA (n = 11, +19 +/- 5%) and significantly decreased renal cortical vascular conductance (RCVC, n = 11, -11 +/- 2%). Passive stretch (n = 20, +378 +/- 11 g) also significantly increased MAP (+11 +/- 2 mmHg), HR (+7 +/- 2 beats min(-1)) and RSNA (n = 15, +14 +/- 4%) and significantly decreased RCVC (n = 11, -12 +/- 3%). RCBF showed no significant changes during static contraction or passive stretch. Renal denervation abolished the decrease in RCVC during contraction (n = 12) or stretch (n = 13). These data indicate that both the exercise pressor reflex and its mechanically sensitive component, the muscle mechanoreflex, induced renal cortical vasoconstriction through sympathetic activation in rats.
authors.affiliation: Graduate School of Engineering Science, Osaka University, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Koba
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Yoshida
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Hayashi
mesh_terms: D000125:Achilles Tendon; D000818:Animals; D001794:Blood Pressure; D002628:Chemoreceptor Cells / Q000502:physiology; D003655:Decerebrate State; D006339:Heart Rate; D007668:Kidney / Q000098:blood supply* / Q000294:innervation; D008297:Male; D009119:Muscle Contraction; D009470:Muscle Spindles / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000378:metabolism; D005082:Physical Exertion / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology*; D012026:Reflex, Stretch; D012079:Renal Circulation / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*; D013979:Tibial Nerve; D014661:Vasoconstriction / Q000502:physiology*