Effects of central osmotic stimulation on vasopressin and enkephalin release into the blood and cerebrospinal fluid and blood pressure.
To assess the central effect of hypertonic NaCl on the release of vasopressin (AVP) and methionine enkephalin-like substances into the blood and cerebrospinal fluid, and on blood pressure, ventriculocisternal perfusion (0.25 ml/min, 60 min) was performed in anesthetized dogs with artificial cerebrospinal fluid (CSF), either isotonic (300 mosmol/kg) or hypertonic (600 and 1200 mosmol/kg). The effect of central administration of a V1-AVP antagonist on the central osmotic challenge was also studied. In dogs, given 600 mosmol/kg, CSF osmolality increased with a concomitant rise in mean arterial pressure and plasma AVP concentrations. Plasma osmolality, heart rate, CSF AVP and plasma and CSF methionine enkephalin-like substances showed no significant change. In dogs, given 1200 mosmol/kg, the CSF osmolality increase was accompanied by a rise in mean arterial pressure, heart rate, plasma AVP and CSF AVP. Plasma osmolality and plasma and CSF methionine-enkephalin-like substances did not change significantly. A V1-AVP antagonist given centrally attenuated the rise in mean arterial pressure induced by osmotic challenge. In dogs, given 300 mosmol/kg, no parameters changed significantly except for a gradual fall in heart rate. These results suggest that central osmotic stimulation by hypertonic NaCl increases blood pressure, heart rate and the release of AVP, but not methionine enkephalin-like substances, into the blood and CSF, and a V1-blocker given centrally attenuates the pressor response.
Ota
K
K
Second Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Kimura
T
T
Matsui
K
K
Iitake
K
K
Shoji
M
M
Inoue
M
M
Sato
K
K
Ohta
M
M
Yamamoto
T
T
Yoshinaga
K
K
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002552:Cerebral Ventricles; D004285:Dogs; D004744:Enkephalin, Methionine / Q000032:analysis* / Q000097:blood / Q000134:cerebrospinal fluid; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D009994:Osmolar Concentration; D010477:Perfusion; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage* / Q000494:pharmacology; D014667:Vasopressins / Q000032:analysis* / Q000097:blood / Q000134:cerebrospinal fluid; D014882:Water-Electrolyte Balance / Q000187:drug effects*
D012462:Saline Solution, Hypertonic; D014667:Vasopressins; D004744:Enkephalin, Methionine