A new telemetric system for arterial blood pressure has recently become popular in experimental studies. In this study, body weight (BW), mean blood pressure (MBP) and heart rate (HR) were measured for 2 or 3 weeks after implantation of a transmitter in 4 strains of rats (F344, Wistar, SHR and WKY) and 1 breed of rabbit (JW) to evaluate the effects of the implantation procedure on their parameters and to confirm their reversibilities.
BW of Wistar and F344 were decreased for 3 days after implantation in each strain, but they began to increase again thereafter and there were no statistically significant difference from each control 3 weeks after implantation. The BW of Wistar rats more rapidly recovered after subcutaneous implantation than after intraperitoneal implantation. The BW of SHR, WKY and JW 2 weeks after implantation of a transmitter recovered to not less than those beforeimplantation.
In SHR, WKY and Wistarrats, basal MBP and HR were noticeobly high just after intraperitoneal implantation, but these values became lower and stable about 1 week after the implantation. The circadian rhythms of MBP and HR were obviously disrupted for the first week, but returned to the nocturnal pattern in the second week except for MBP in WKY. In JW, MBP and HR were tended to be high for 6 and 2 days after implantation, respectively, but became stable thereafter. The circadian rhythms of MBP and HR in JW were disturbed for a few days, but then returned to the nocturnal patterns, as was the case in rats.
We concluded that the recovery period after intraperitoneal (rats) or subcutaneous (rabbits) implantation of transmitter should be 2 or 3 weeks in view of the BW and 1 week in view of basal values and circadian rhythms in MBP and HR.

View full abstract

Pathological examination was performed on the pulmonary artery of five raccoon dogs (Nyctereutes procyonoides) infected with Dirofilaria immitis. The most significant vascular change exhibited villous intimal proliferation in both the pulmonary trunk and the right and left branches, as the extrapulmonary arteries. The lesion of intimalproliferation was also found in the intrapulmonary artery rich in elastic fibers in all lung lobes, predominantly in the right caudal lobe. In addition, the intrapulmonary arteries revealed fibrous and cellular intimal thickening without villous formation and such a lesion with medial hypertrophy. These pulmonary arterial lesions associated with Dirofilaria immitis infection in raccoon dogs were consistent with those seen in dogs with dirofilariasis in quality, and the lesions were quantitatively more severe than those in dogs.

View full abstract

The aorta was examined pathologically in 20 dogs ranging in age from 10 to 18 years. Macroscopically, rough appearance of the intimal surface of the aorta was found in 17 dogs : 6 animals showed white linear or streak-like plaque formation on the intimal surface. Microscopically, many portions of the aorta examined exhibited degenerative or sclerotic changes in the intima, internal elastic membrane and media. Intimal lesions characterized by mild to severe thickening were classified into 3 types according to their main components : muscular, fibrous and fibromuscular thickening. An alteration in the internal clastic membrane consisted of partial loss, splitting, fragmentation, reduplication, and calcium deposition, and almost always coexisted together with the intimal lesions in most sections. In the media, edematous swelling of the smooth muscle cells surrounded by edematous accumulation was observed as the earliest evidence of the medial degeneration, which was followed by the presence of relatively dense fibrous tissue with a focal loss of muscle, leading to extensive medial fibrosis. These fibrotic lesions were more frequently observed in the cases with pronounced intimal thickening. The severity of such lesions in the vascular walls appeared to be associated with increasing age. In addition, the severer lesions tended to occur frequently at more distal portions of the aorta. The vascular changes observed in the present study resembled those seen in senile arteriosclerosis in man.

View full abstract

This study was aimed to identify the stimulus mechanisms and neural pathway of water-induced respiratory and cardiovascular reflexes originating in the nasal cavity in rabbits with the upper airway isolated, breathing through a tracheostomy or having artificial ventilation. The superior laryngeal nerves (SLNs) were previously sectioned. A conspicuous inhibition of breathing (apnea), bradycardia, a rise in systemic blood pressure and also a vise in left ventricular pressure followed by its fall were elicited by the instillation of distilled water (38°C), but not by saline (38°C), into the nasal cavity. These reflexes could be consistently induced in rabbits with a dennervation of the glossopharyngeal nerves together with the SLNs, indicating that the most adequate stimulus site of these reflexes is the nasal cavity and the most possible neural pathway is the trigeminal nerve. Isotonic solution of glucose (6%, 38°C) failed to elicite these reflexes, suggesting that hypoosmolarity is a main stimulus factor. Since cold saline (12°C) could also cause similar reflexes, but much weaker than that in distilled water-stimulation (38°C), the decrease in temperature is one of factors enhancing the reflexes. The bradycardia was inhibited to some extent (13% decrease in heart rate) by distilled water applied under the artificial ventilation and was able to be induced by transienly stopping of aritificial ventilation. Therefore, some bradycardia was secondarily elicited by the occurrence of apnea. Further experiments with autonomic nerve blockades demonstrated the predominant effects of the parasympathetic mechanism on the heart and the sympathetic mechanism on the peripheral vascular system.

View full abstract

Balloon dilation was performed to the aortic stenosis of three golden retrievers. No clinical signs except cardiac murmurs were found in two of three cases but less motion or mild pulmonary edema (No.3) was examined in remaining one case at the first clinical examinations. An aortic flow velocity (AOF) which suggested the severity of aortic stenosis was more than 6.0 m/sec in three cases. A pressure gradient by Doppler echocardiogram was calculated between 70.2 to 189.0 mmHg. To these cases, 7F and 9F balloon dilation catheters were used to repair the aortic stenosis and it was inserted into the left ventricle outflow tract through the left carotid artery. Balloon was inflated three or four times for about ten seconds to dilate the stenosis.
AOF was reduced 1.0 to 3.0 m/sec after the dilation, and pressure gradient was also reduced 30.0 to 107 mmHg. No restenosis was found after surgery but mitral stenosis, in one case, was diagnosed. Therefore, it is necessary to have the clinical examinations periodically.

View full abstract