Responses of the canine myocardium to stimulation of thoracic cardiac nerves

1977 ◽  
Vol 232 (5) ◽  
pp. H485-H494 ◽  
Author(s):  
J. E. Norris ◽  
W. C. Randall
Keyword(s):  
Blood Pressure ◽  
Systemic Blood Pressure ◽  
Type Ii ◽  
Systemic Blood ◽  
Type Iv ◽  
The Right ◽  
Alpha Chloralose ◽  
Canine Myocardium ◽  
Cardiac Nerves ◽  
Stimulation Of

The thoracic cardiac nerves were stimulated in each of 21 dogs anesthetized with alpha chloralose. Recordings were made of heart rate, blood pressure, and contractile force from all four cardiac chambers. Walton-Brodie strain-gauge arches were sutured to both atria, and to three locations of each ventricle, representing both anterior and posterior surfaces. The functional autonomic components of each nerve were summarized and classified into four basic types. Types I and II were both located medial to the thoracic vagi. These were shown to contain both sympathetic and parasympathetic components traveling to all four chambers of the heart. The sympathetic componnent of the type II nerves produced reflex changes in force of contraction and systemic blood pressure. Nerves classified as types III and IV produced no parasympathetic effect on the heart. These were all located lateral to the thoracic vagi. While the type III nerves carried sympathetic efferent fibers to all four chambers, the type IV nerve carried sympathetic fibers predominantly to the right atrium.

scholarly journals Intraocular pressure in postmenopausal Nigerian women with and without systemic hypertension

2011 ◽  
Vol 70 (3) ◽  
Author(s):  
J. A. Ebeigbe ◽  
P. N. Ebeigbe ◽  
A. D. A Ighoroje
Keyword(s):  
Blood Pressure ◽  
Intraocular Pressure ◽  
Postmenopausal Women ◽  
Systemic Blood Pressure ◽  
Systemic Hypertension ◽  
Systemic Blood ◽  
Nigerian Women ◽  
The Difference ◽  
Post Menopausal ◽  
The Right

Background: Mean intraocular pressure (IOP) in postmenopausal women has been reported higher than that in menstruating women. Also, intraocular pressure is said to be positively correlated with systemic blood pressure. No previous study in Nigeria has compared intraocular pressure in postmenopausal women with and without systemic hypertension. Purpose: To investigate the effects of menopause on intraocular pressure in subjects with and without high blood pressure. Methods: Normotensive and hypertensive premenopausal and postmenopausal subjects in the   same agerange of 45 to 55 years were studied. Intraocular pressure was measured with the hand-held Kowa applanation tonometer.  Blood pressure was taken in the sitting position at the right upper arm using a manual mercury sphygmomanometer with the right cuff size. The average of two readings was recorded. Results: Mean IOP for premenopausal normotensive women was 14.58 ± 2.56 mmHg whilethat of postmenopausal normotensive women was16.15 ± 1.80 mmHg (p<0.05).  Also, the difference in mean IOP between premenopausal hypertensive (16.58 ± 3.23 mmHg) and postmenopausal hypertensive women (18.24 ± 3.89 mmHg)was statistically significant (p<0.05). A statistically significant and positive correlation was observed between IOP and systemic blood pressure in postmenopausal hypertensive women, p<0.05.Conclusion: Menopause significantly increases intraocular pressure. Mean intraocular pressure of hypertensive postmenopausal women was significantly higher than that of normotensive post-menopausal women, (p<0.05). Knowledge of the normal level of intraocular pressure during various stages of the female reproductive cycle may help during glaucoma screening. (S Afr Optom 2011 70(3) 117-122)

Ventricular Outflow Dynamics in the Lizard, Varanus Niloticus: Responses to Hypoxia, Hypercarbia and Diving

1974 ◽  
Vol 60 (3) ◽  
pp. 871-880 ◽  
Author(s):  
R. W. MILLARD ◽  
K. JOHANSEN
Keyword(s):  
Blood Pressure ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pressure Rise ◽  
Systemic Blood Pressure ◽  
Aortic Pressure ◽  
Systemic Resistance ◽  
Systemic Blood ◽  
Normal Breathing ◽  
The Right

1. Blood flow and blood pressure have been measured in the right aorta and left pulmonary artery of the semi-aquatic lizard, Varanus niloticus, during normal breathing, during hypercarbic and hypoxic breathing and during voluntary diving. 2. Mean pulmonary blood pressure during normal breathing was 19.5±2.0 cmH2O while right aortic pressure was 118.0±3.0 cmH2O. The high systemic blood pressure and high ratio of systemic to pulmonary vascular resistance (4.0-6.0) stand out among reptiles and approach values in homeotherm vertebrates. 3. Pulmonary pressure rise preceded right aortic pressure rise by 120 msec at a heart rate of 25/min. Pulmonary ejection lasted 50% of the cardiac cycle compared to 25% for aortic ejection during normal breathing. 4. CO2 breathing increased right aortic vascular resistance by 120% while pulmonary resistance increased moderately by 30%. Carotid vascular resistance decreased during CO2 breathing. The pulmonary blood pressure increase was however much higher than the systemic, but at no time did systemic and pulmonary blood pressures overlap. 5. Hypoxic breathing increased pulmonary blood pressure to 36.0±4.0 cmH2O while right aortic pressure fell to 100.0±10.0 cmH2O. Ejection time remained unchanged in the right aorta while pulmonary flow became continuous. Overall pulmonary vascular resistance increased markedly while systemic resistance changed little. 6. Voluntary diving increased pulmonary blood pressure while the systemic blood pressure fell markedly. 7. The results obtained are discussed in the light of ventricular outflow distribution in reptiles. Directional shunting of blood inside the heart of V. niloticus during cardiac systole must be reduced or absent. Intracardiac shunting during cardiac filling or by systolic residual volumes is small, placing varanid lacertilians haemodynamically closer to homoetherm vertebrates than other reptiles studied.

Methylprednisolone on circulating eicosanoids and vasomotor tone after endotoxin

1986 ◽  
Vol 61 (1) ◽  
pp. 185-191 ◽  
Author(s):  
C. A. Hales ◽  
R. D. Brandstetter ◽  
C. F. Neely ◽  
M. B. Peterson ◽  
D. Kong ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Vascular Resistance ◽  
Systemic Blood Pressure ◽  
Physiological Effect ◽  
High Dose ◽  
Systemic Blood ◽  
Eicosanoid Production ◽  
Circulating Levels

Acute pulmonary and systemic vasomotor changes induced by endotoxin in dogs have been related, at least in part, to the production of eicosanoids such as the vasoconstrictor thromboxane and the vasodilator prostacyclin. Steroids in high doses, in vitro, inhibit activation of phospholipase A2 and prevent fatty acid release from cell membranes to enter the arachidonic acid cascade. We, therefore, administered methylprednisolone (40 mg/kg) to dogs to see if eicosanoid production and the ensuing vasomotor changes could be prevented after administration of 150 micrograms/kg of endotoxin. The stable metabolites of thromboxane B2 (TxB2) and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) were measured by radioimmunoassay. Methylprednisolone by itself did not alter circulating eicosanoids but when given 2.5 h before endotoxin not only failed to inhibit endotoxin-induced eicosanoid production but actually resulted in higher circulating levels of 6-keto-PGF1 alpha (P less than 0.05) compared with animals receiving endotoxin alone. Indomethacin prevented the steroid-enhanced concentrations of 6-keto-PGF1 alpha after endotoxin and prevented the greater fall (P less than 0.05) in systemic blood pressure and systemic vascular resistance with steroid plus endotoxin than occurred with endotoxin alone. Administration of methylprednisolone immediately before endotoxin resulted in enhanced levels (P less than 0.05) of both TxB2 and 6-keto-PGF1 alpha but with a fall in systemic blood pressure and vascular resistance similar to the animals pretreated by 2.5 h. In contrast to the early steroid group in which all of the hypotensive effect was due to eicosanoids, in the latter group steroids had an additional nonspecific effect. Thus, in vivo, high-dose steroids did not prevent endotoxin-induced increases in eicosanoids but actually increased circulating levels of TxB2 and 6-keto-PGF1 alpha with a physiological effect favoring vasodilation.

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