Functional relationship between subfornical organ cholinergic stimulation and nitrergic activation influencing cardiovascular and body fluid homeostasis.
We have studied the effects of L-NG-nitro arginine methyl esther (L-NAME), L-arginine (LAR), inhibitor and a donating nitric oxide agent on the alterations of salivary flow, water intake, arterial blood pressure (MAP) and heart rate (HR) induced by the injection pilocarpine into the subfornical organ (SFO). Rats (Holtzman 250-300 g) were anesthetized with 2, 2, 2-tribromoethanol (20 mg/100 kg b. wt.) and a stainless steel cannula were implanted into their SFO. The volume of injection was 0.2 microl. The amount of saliva secretion was studied over a 5-min period. Pilocarpine (40 microg), L-NAME (40 microg) and LAR (30 microg) were used in all experiments for the injection into the SFO. Pilocarpine (10, 20, 40, 80 and 160 microg) injected into SFO elicited a concentration-dependent increase in salivary secretion. L-NAME injected prior to pilocarpine into the SFO increased salivary secretion and water intake due to the effect of pilocarpine. LAR injected prior to pilocarpine into the SFO attenuated the salivary secretion and water intake. Pilocarpine, injected into the SFO increased the MAP and decreased heart rate (HR). L-NAME injected prior to pilocarpine into the SFO potentiated the pressor effect of pilocarpine with a decrease in HR. LAR injected into the SFO prior to pilocarpine attenuated the increase in MAP with no changes in HR. The present study suggests that the SFO nitrergic cells interfere in the cholinergic pathways implicated in the control of salivary secretion, fluid and cardiovascular homeostasis.
Saad
Wilson Abrão
WA
Basic Institute of Biosciences-UNITAU, Taubaté, SP, Brazil. saad@foar.unesp.br
Guarda
Ismael Francisco Motta Siqueira
IF
Camargo
Luis Antonio de Arruda
LA
dos Santos
Talmir Augusto Faria Brisola
TA
Saad
William Abrão
WA
D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001826:Body Fluids / Q000187:drug effects / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D004326:Drinking / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects*; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000008:administration & dosage / Q000494:pharmacology; D010862:Pilocarpine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D012463:Saliva / Q000187:drug effects; D012472:Salivation / Q000187:drug effects; D013356:Subfornical Organ / Q000187:drug effects* / Q000502:physiology
D004791:Enzyme Inhibitors; D018721:Muscarinic Agonists; D020030:Nitric Oxide Donors; D010862:Pilocarpine; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester