Electrical stimulation of the rabbit pulmonary artery increases respiratory output

2004 ◽  
Vol 140 (3) ◽  
pp. 209-217 ◽  
Author(s):  
Yasumasa Okada ◽  
Tohru Satoh ◽  
Shun-ichi Kuwana ◽  
Masanori Kashiwagi ◽  
Tatsumi Kusakabe
Keyword(s):  
Electrical Stimulation ◽  
Pulmonary Artery ◽  
Rabbit Pulmonary Artery ◽  
Stimulation Of

scholarly journals VAGAL REGULATION OF INTRACARDIAC SHUNTING IN THE TURTLE PSEUDEMYS SCRIPTA

1994 ◽  
Vol 186 (1) ◽  
pp. 109-126 ◽  
Author(s):  
J. Hicks ◽  
S. Comeau
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Pulmonary Artery ◽  
Left Atrium ◽  
Jugular Vein ◽  
Left And Right ◽  
The Right ◽  
Right Atria ◽  
Intracardiac Shunting ◽  
Stimulation Of

Two principal hypotheses account for intracardiac shunting in reptiles. The ‘pressure shunting’ hypothesis proposes that there is no fuctional separation between the ventricular cava during systole. The ‘washout shunting’ hypothesis suggests that the cavum pulmonale is functionally separated from the rest of the ventricle during systole. The purpose of this study was to test the two principal hypotheses in a turtle, Pseudemys scripta, after inducing a right-to-left shunt by electrical stimulation of the vagus nerve. Animals were anaesthetized with sodium pentobarbital (30–40 mg kg-1), tracheotomized and mechanically ventilated. Two experimental groups were used. Both groups had the right and left cervical vagi exposed and sectioned and silver bipolar electrodes were attached for electrical stimulation. In addition, cardiac function was evaluated by determining the pulmonary blood flow, pulmonary arterial pressure, peak systolic pressure in the cavum pulmonale, central arterial pressure, pulmonary vascular resistance and heart rate. In group I, hydrogen electrodes were inserted into the right aorta, the left aorta and the pulmonary artery. Hydrogen, dissolved in saline, was infused into the left atrium, jugular vein and cavum pulmonale. Blood flow from these sites was deduced from detection of a H2 signal in the right and left aortae and the pulmonary artery. In group II, catheters were inserted in the left and right atria and aortae for the measurement of blood gases. For both groups, the protocol consisted of control periods and periods of electrical stimulation of the efferent and afferent ends of the vagus nerve. During the control periods, infusion of a H2 solution into either the left atrium or the jugular vein resulted in the detection of H2 in the right and left aortae and the pulmonary artery. This suggested that both right-to-left and left-to-right intracardiac shunts were present. H2 infused into the cavum pulmonale was always detected in the pulmonary artery but never in the left or right aortae. During stimulation of the right vagal efferents, a bradycardia developed (heart rate declined by 65 %), pulmonary blood flow was reduced by 73 % and pulmonary vascular resistance increased by 158 %. This was accompanied by a reduction in the PO2 of both the right and left aortae, although the PO2 of the left and right atria remained constant. Under these conditions, H2 infused into the jugular vein and the left atrium was detected in the right and left aortae and the pulmonary artery of all animals studied. Infusion of H2 into the cavum pulmonale was detected in the right and left aortae in only two animals. The results supported the washout mechanism for right-to-left intracardiac shunting.

ADENOHYPOPHYSEAL LH CONTENT IN NORMAL, ANDROGEN-STERILIZED AND PROGESTERONE-PRIMED STERILE FEMALE RATS

1962 ◽  
Vol 39 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Roger A. Gorski ◽  
Charles A. Barraclough
Keyword(s):  
Ascorbic Acid ◽  
Electrical Stimulation ◽  
Quantitative Determination ◽  
Median Eminence ◽  
Hypothalamic Stimulation ◽  
Female Rats ◽  
Rat Pituitary ◽  
Gland Content ◽  
Stimulation Of

ABSTRACT We have previously suggested that the failure of the androgen-sterilized, persistent-oestrous rat to ovulate, following electrical stimulation of the median eminence structures of the hypothalamus, is due to an insufficiency in adenohypophyseal LH concentration. Using the ovarian ascorbic acid technique for quantitative determination of pituitary LH content, the present studies have demonstrated that the sterile rat pituitary gland contains one-third the LH content of the normal prooestrous gland. Furthermore, not only does progesterone priming of this persistent-oestrous rat result in a 75 % increase in LH concentration, but on hypothalamic stimulation sufficient LH is released to induce ovulation. The decrease in LH concentration which accompanies ovulation in the progesterone-primed, sterile rat is approximately 45 % of the total gland content as compared with a 51 % decrease in pituitary content in the normal cyclic rat.

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