Sodium nitroprusside blocks the cat carotid chemosensory inhibition induced by dopamine, but not that by hyperoxia

We studied the effects of the nitric oxide (NO) synthase inhibitor, Nω- nitro-L-arginine methyl ester (L-NAME), and the NO donor, sodium nitroprusside (SNP) on cat chemosensory responses to intravenous injections of NaCN (0.1-100 μg/kg) and dopamine (0.1-20 μg/kg), and to hyperoxic ventilation (100% O2, 60-120 s). Cats were anesthetized with sodium pentobarbitone, paralyzed and artificially ventilated to prevent secondary ventilatory effects. The frequency of chemosensory discharges (f(x)) was recorded from one sectioned carotid sinus nerve. L-NAME (50 mg/kg i.v.) increased basal f(x) and slightly potentiated the responses to NaCN and dopamine. SNP (1-2 mg/kg i.v.) increased basal f(x), but reduced the NaCN- induced increases of f(x) over baseline and the transient f(x) inhibitions induced by dopamine, but not those produced by hyperoxia. Present results indicate that besides the known inhibitory effect of NO on chemosensory responses to low PO2, NO also blocks the chemosensory respon

Endothelins in the cat petrosal ganglion and carotid body: Effects and immunolocalization

In response to hypoxia, chemoreceptor cells of the carotid body (CB) release transmitters, which acting on the petrosal ganglion (PG) neuron terminals, increase the chemoafferent discharge. Additionally, vasoactive molecules produced within the CB may modulate hypoxic chemoreception by controlling blood flow and tissue PO2. Endothelin-1 (ET-1) increases basal CB chemosensory discharges in situ, probably due to its vasoconstrictor action. However, the actions of ET-1 on PG neurons or its expression in the PG are not known. Using immunohistochemistry, we found that endothelin-like peptides are expressed in the cat PG and CB under normoxic conditions. Exogenous applications of ET- 1 increased the chemosensory activity in the vascularly perfused CB but were ineffective on either the CB or PG superfused preparations, both of which are devoid of vascular control. Thus, our data indicate that the excitatory effect of ET-1 in the carotid chemoreceptor system appears to be mainly due to a vasoconstrictor effect in the CB blood vessels.This work was supported by grant 1030330 from the National Fund for Scientific and Technological Development of Chile (FONDECYT)

Enfermedades transmisibles

Investigación de un brote por Salmonella entérica serotipo enteritidis, en una clínica privada, Región Metropolitana&nbsp

Enfermedades transmisibles

Investigación de un brote por Salmonella entérica serotipo enteritidis, en una clínica privada, Región Metropolitana&nbsp