Biomaterial Database

Aortic and carotid chemoreceptor responses to metabolic acidosis in the cat. 1983

M Pokorski, and S Lahiri

The effect of metabolic acidosis on the activity of aortic chemoreceptor afferents and their responses to hypoxia and hypercapnia were investigated in nine cats anesthetized with alpha-chloralose, paralyzed, and artificially ventilated. This effect was compared with that on simultaneously recorded activity of carotid chemoreceptor afferents in three separate cats. The activity of a single or paucifiber preparation of chemoreceptor afferents was recorded at five steady-state levels of arterial O2 tension (PaO2) at a constant arterial CO2 tension (PaCO2) and at three levels of PaCO2 during hyperoxia (PaO2 greater than 400 Torr) before and after slow injection of 1 M lactic acid in the average dose of 2.6 +/- 0.6 mmol X kg-1. On the average, arterial pH decreased from 7.445 +/- 0.046 to 7.222 +/- 0.041 at PaO2 of 98 +/- 5 Torr and PaCO2 of 34 +/- 1 Torr. This decrease in pHa during normoxia increased the aortic chemoreceptor activity from 0.8 +/- 0.2 to 1.4 +/- 0.3 imp X s-1. Metabolic acidosis increased the excitatory effect of hypoxia and hypercapnia. The stimulatory effect of CO2 for the same increase in arterial [H+] was greater than that of metabolic acidosis, indicating a dominant effect of molecular CO2 on aortic chemoreceptors. Simultaneous measurements of carotid and aortic chemoreceptor activities showed that their responses to metabolic acidosis were qualitatively similar. Quantitatively, the response of aortic chemoreceptor afferents was less than that of carotid chemoreceptors.

UI	MeSH Term	Description	Entries
D007773	Lactates	Salts or esters of LACTIC ACID containing the general formula CH3CHOHCOOR.
D008297	Male		Males
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D010313	Partial Pressure	The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Partial Pressures,Pressure, Partial,Pressures, Partial
D002344	Carotid Body	A small cluster of chemoreceptive and supporting cells located near the bifurcation of the internal carotid artery. The carotid body, which is richly supplied with fenestrated capillaries, senses the pH, carbon dioxide, and oxygen concentrations in the blood and plays a crucial role in their homeostatic control.	Glomus Caroticum,Bodies, Carotid,Body, Carotid,Caroticum, Glomus,Carotid Bodies
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D002628	Chemoreceptor Cells	Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.	Chemoreceptive Cells,Cell, Chemoreceptive,Cell, Chemoreceptor,Cells, Chemoreceptive,Cells, Chemoreceptor,Chemoreceptive Cell,Chemoreceptor Cell
D005260	Female		Females
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D006935	Hypercapnia	A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood.