Timolol plus acetazolamide: effect on formation of cerebrospinal fluid in cats and rats

1985 ◽  
Vol 63 (4) ◽  
pp. 340-343 ◽  
Author(s):  
Betty P. Vogh ◽  
David R. Godman
Keyword(s):  
Cerebrospinal Fluid ◽  
Nervous System ◽  
Carbonic Anhydrase ◽  
Sympathetic Nervous System ◽  
Adrenergic Receptors ◽  
Beta Adrenergic Receptors ◽  
Beta Adrenergic ◽  
Sympathetic Nervous ◽  
Combined Drugs

Administration iv of 50 mg∙kg−1 acetazolamide (A) and 3 mg∙kg−1 timolol (T) causes the formation of cerebrospinal fluid (f-CSF) to be reduced to 43.7% of the control rate compared with a reduction to 82.5% of control by T alone and to 52.6% of control by A alone. The effect of combined drugs is the same when A is combined with T initially, when A is added to T after studying T alone, or when T is added to A after studying A alone. In contrast, in rats f-CSF is not influenced by T, either alone or when in combination with A. The rate in rats is reduced to 55% of control by treatments with A or A and T. Decrease in formation of cerebrospinal fluid by A occurs through inhibition of carbonic anhydrase, but the means whereby T (a known blocker of beta-adrenergic receptors) causes a reduction in f-CSF is not established; it is known that it does not inhibit carbonic anhydrase. Control of f-CSF by the sympathetic nervous system is discussed.

Ontogeny of canine intrathoracic cardiac nervous system

1991 ◽  
Vol 261 (4) ◽  
pp. R920-R927 ◽  
Author(s):  
C. Haddad ◽  
J. A. Armour
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Adrenergic Receptors ◽  
Beta Agonist ◽  
Canine Heart ◽  
Cardiac Innervation ◽  
Beta Adrenergic Receptors ◽  
Parasympathetic Innervation ◽  
Beta Adrenergic ◽  
Sympathetic Nervous

The functional cardiac innervation of 61 puppies from nine different litters (2-8 littermates), ranging in age from 1 day to 7 wk, was investigated. The efferent sympathetic nervous system exerted minimal effects on the heart of 1-day-old puppies, gradually influencing the heart more thereafter such that by 7 wk of life it was functionally mature. In contrast, efferent parasympathetic cardiac innervation was well developed at birth, maturing thereafter such that by 4-7 wk of age its capacity to modulate the heart was similar to that found in adults. The right- and left-sided efferent sympathetic and parasympathetic intrathoracic nervous systems induced similar cardiac modulation throughout this period of development. Cardiac myocyte beta-adrenergic receptors were partially functional at birth, as determined by responses elicited by supramaximal doses of the beta-agonist isoproterenol. Responses elicited by isoproterenol became greater over the following 7 wk of life, when they were found to be similar to those elicited in adults. By 1 wk of age, synaptic mechanisms in intrathoracic sympathetic ganglia involved in cardiac regulation were relatively well developed, with cardiopulmonary-cardiac reflexes present but not functionally mature at that age. It is concluded that maturation of the efferent sympathetic nervous system modulating the canine heart depends to a large extent on the ontogeny of cardiac beta-adrenergic receptors rather than the ontogeny of synapses in intrathoracic ganglia. Furthermore, even though functional cardiac efferent parasympathetic innervation is present before efferent sympathetic innervation, both reach maturity at about the same age.

Inhibitory control of proximal colonic motility by the sympathetic nervous system

1987 ◽  
Vol 253 (4) ◽  
pp. G531-G539 ◽  
Author(s):  
R. A. Gillis ◽  
J. Dias Souza ◽  
K. A. Hicks ◽  
A. W. Mangel ◽  
F. D. Pagani ◽  
...  
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Nerve Stimulation ◽  
Adrenergic Receptors ◽  
Vagal Stimulation ◽  
Colonic Motility ◽  
Inhibitory Effect ◽  
Proximal Colon ◽  
Pelvic Nerve ◽  
Sympathetic Nervous

The purpose of this study is to determine whether or not the sympathetic nervous system provides a tonic inhibitory input to the colon in chloralose-anesthetized cats. Proximal and midcolonic motility were monitored using extraluminal force transducers. An intravenous bolus injection of 5 mg of phentolamine in 14 animals elicited a pronounced increase in proximal colon contractility. The minute motility index changed from 0 +/- 0 to 26 +/- 4 after phentolamine administration. Midcolonic motility also increased in response to phentolamine. Specific blockade of alpha 2-receptors, but not alpha 1-receptors, caused the same response seen with phentolamine. alpha-Adrenergic blockade increased colon contractility after spinal cord transection but not after ganglionic blockade. Blockade of alpha-adrenergic receptors was also performed before vagal and pelvic nerve stimulation and in both cases increased colonic motility. Vagal stimulation alone had no effect on colonic contractility, while pelvic nerve stimulation increased motility at the midcolon. alpha-Receptor blockade did not alter the ineffectiveness of vagal stimulation but did unmask excitatory effects of pelvic nerve stimulation on the proximal colon. All excitatory colonic responses were prevented by blocking muscarinic cholinergic receptors. These data indicate that tonic sympathetic nervous system activity exerts an inhibitory effect on colonic motility. The inhibitory effect is mediated through alpha 2-adrenergic receptors. Based on these findings, we suggest that alterations in sympathetic nervous system activity may be extremely important for the regulation of circular muscle contractions in the colon.

Influence of sodium concentration in cerebrospinal fluid on plasma atrial natriuretic peptide in conscious rats

1988 ◽  
Vol 74 (1) ◽  
pp. 49-52 ◽  
Author(s):  
Yuhei Kawano ◽  
Kaoru Yoshida ◽  
Yukio Hirata ◽  
Hiroki Yoshimi ◽  
Morio Kuramochi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cerebrospinal Fluid ◽  
Nervous System ◽  
Sympathetic Nervous System ◽  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Sodium Concentration ◽  
Intracerebroventricular Infusion ◽  
Sympathetic Nervous ◽  
Atrial Natriuretic

1. To test the influence of a sodium (Na+) stimulus within the central nervous system on the release of atrial natriuretic peptide (ANP), we examined the effects of intracerebroventricular infusion of high Na+ artificial cerebrospinal fluid (CSF) on blood pressure, urinary Na+ excretion and plasma ANP levels in conscious Wistar rats. 2. Infusion of high Na+ (0.6 mol/1) CSF into the lateral ventricle at a rate of 1 μl/min for 60 min significantly increased mean blood pressure and urinary Na+ excretion, while normal Na+ (0.15 mol/1) CSF had no effects. Plasma ANP levels were higher in the high Na+ CSF group than in the normal Na+ group (154 ±39 vs 52 ±19 pmol/l, P < 0.05). 3. Interruption of the sympathetic nervous system and the vascular action of vasopressin with intravenous hexamethonium and d(CH2)5Tyr(Me)arginine vasopressin attenuated the pressor and natriuretic responses to intracerebroventricular high Na+ CSF. Plasma ANP levels in these rats did not differ significantly from those in rats which were similarly treated but were given normal Na+ CSF. 4. These results indicate that elevation of the CSF Na+ concentration without peripheral volume loading can stimulate ANP release into the circulation. ANP release due to central Na+ stimulus appears to be mediated by the sympathetic nervous system, vasopressin, and/or haemodynamic change caused by these factors.

BETA-ADRENERGIC MEDIATION OF SYMPATHETIC NERVOUS SYSTEM ACTIVITY

1982 ◽  
Vol 10 (3) ◽  
pp. 221
Author(s):  
Bart Chernow ◽  
Michael Ziegler ◽  
Joseph Coyle ◽  
David Cruess ◽  
Pat Hughes ◽  
...  
Keyword(s):  
Nervous System ◽  
Sympathetic Nervous System ◽  
Sympathetic Nervous System Activity ◽  
Beta Adrenergic ◽  
System Activity ◽  
Nervous System Activity ◽  
Sympathetic Nervous
Sign in / Sign up

Export Citation Format

Share Document