Biomedical subjects

C Y Chai

Publications and source records attributed to C Y Chai.

At least 37 records · Page 2Linked to original sources

PubMed2001

Tumor-specific immunity and antiangiogenesis generated by a DNA vaccine encoding calreticulin linked to a tumor antigen.

Antigen-specific cancer immunotherapy and antiangiogenesis have emerged as two attractive strategies for cancer treatment. An innovative approach that combines both mechanisms will likely generate the most potent antitumor effect. We tested this approach using calreticulin (CRT), which has demonstrated the ability to enhance MHC class I presentation and exhibit an antiangiogenic effect. We explored the linkage of CRT to a model tumor antigen, human papilloma virus type-16 (HPV-16) E7, for the development of a DNA vaccine. We found that C57BL/6 mice vaccinated intradermally with CRT/E7 DNA exhibited a dramatic increase in E7-specific CD8(+) T cell precursors and an impressive antitumor effect against E7-expressing tumors compared with mice vaccinated with wild-type E7 DNA or CRT DNA. Vaccination of CD4/CD8 double-depleted C57BL/6 mice and immunocompromised (BALB/c nu/nu) mice with CRT/E7 DNA or CRT DNA generated significant reduction of lung tumor nodules compared with wild-type E7 DNA, suggesting that antiangiogenesis may have contributed to the antitumor effect. Examination of microvessel density in lung tumor nodules and an in vivo angiogenesis assay further confirmed the antiangiogenic effect generated by CRT/E7 and CRT. Thus, cancer therapy using CRT linked to a tumor antigen holds promise for treating tumors by combining antigen-specific immunotherapy and antiangiogenesis.

Animals↗

PubMed2001

Effects of dexamethasone on emesis in cats sedated with xylazine hydrochloride.

OBJECTIVE: To determine antiemetic efficacy of prophylactic administration of dexamethasone and its influence on sedation in cats sedated with xylazine hydrochloride. ANIMALS: 6 healthy adult cats (3 males and 3 females). PROCEDURE: The prophylactic antiemetic effect of 4 doses of dexamethasone (1, 2, 4, and 8 mg/kg of body weight, IM) or saline (0.9% NaCl) solution (0.066 ml/kg, IM) administered 1 hour before administration of xylazine (0.66 mg/kg, IM) was evaluated. Cats initially were given saline treatment (day 0) and were given sequentially increasing doses of xylazine on days 7, 14, 21, and 28. After xylazine injection, all cats were observed for 30 minutes to allow assessment of frequency of emesis and time until onset of the first emetic episode. The influence of dexamethasone on xylazine-induced sedation in these cats also was evaluated. RESULTS: Prior treatment with 4 or 8 mg/kg of dexamethasone significantly reduced the frequency of emetic episodes and also significantly prolonged the time until onset of the first emetic episode after xylazine injection. Time until onset of the first emetic episode also was significantly prolonged for dexamethasone at a dose of 2 mg/kg. Time until onset of sedation after administration of xylazine was not altered by administration of dexamethasone. CONCLUSIONS AND CLINICAL RELEVANCE: Dexamethasone (4 or 8 mg/kg, IM) significantly decreased the frequency of emetic episodes induced by xylazine without compromising sedative effects in cats. Dexamethasone may be used prophylactically as an antiemetic in cats treated with xylazine.

Adrenergic alpha-Agonists↗

PubMed2001

Expression of HER-2/NEU oncoprotein in familial and non-familial breast cancer.

The HER-2/neu proto-oncogene amplification or oncoprotein overexpression is an important prognostic factor and a predictive factor for resistance to endocrine therapy and adjuvant chemotherapy in breast cancers. Moreover, it is an entry criterion in the assessment of patients for whom Herceptin (Trastuzumab) treatment is considered. The overexpression rate of HER-2/neu oncoprotein has been identified in 10% to 40% of human breast cancers. In Taiwan, a higher grade of pathobiologic characteristics of familial breast cancer was also noted than that found in the non-familial group. It is worthwhile to evaluate whether the overexpression is more frequent in familial breast cancers. Fifty-six familial and 111 non-familial breast cancers were studied between 1990 and 1999 to assess both the overexpression of HER-2/neu oncoprotein immunohistochemically and the correlation with the histological type, grade and stage of breast carcinoma. The overexpression rate is higher in the familial breast cancer group (50.0%) when compared with non-familial breast cancer group (36.9%), which did not prove to be statistically significant (P = 0.1068). However, when the infiltrating ductal carcinomas of both groups are compared, it is statistically significant (52.3% vs. 33.7%, P = 0.0429). Overexpression correlated with node status and histological grade of infiltrating ductal carcinomas in non-familial and overall breast cancers. It also correlated with nuclear pleomorphism and mitotic counts, but not tubule formation or tumor size. All 3 cases of Paget's disease revealed overexpression, whereas all 12 cases of mucinous and one case of metaplastic carcinoma and one case of medullary carcinoma were negative. The overexpression rate was higher both in familial and non-familial intraductal carcinomas (57.1% vs. 73.3%, P = 0.4716). No statistical difference was identified between the 2 subsets. A case of infiltrating ductal carcinoma combined with intraductal carcinoma revealed heterogeneous staining in the component of ductal carcinoma in situ, while the invasive component did not. This suggests that overexpression decreases within individual tumors as they evolve from in situ to invasive lesioins. The HER-2/neu may imply a different role in intraductal carcinoma, Paget's disease and invasive duct carcinoma. Although the overexpression rate of HER-2/neu oncoprotein of familial breast cancer was not significantly higher than that of the non-familial group, it is appropriate to evaluate the rate of HER-2/neu overexpression according to the histological type of breast cancers from familial breast cancer and non-familial breast cancer. The prognoses will be needed for future evaluation.

Breast Neoplasms↗

PubMed2001

Expression of transforming growth factor-beta 1 and alpha-smooth muscle actin of myofibroblast in the pathogenesis of nasal polyps.

The pathophysiology of nasal polyps remains unclear, but recent work suggests that many cytokines are produced in nasal polyps (NPs) and that they may play various important roles in the pathogenesis of NPs. Transforming growth factor-beta 1 (TGF-beta 1), secreted by many inflammatory cells, is a potent inducer of myofibroblasts. Myofibroblasts express alpha-smooth muscle actin (alpha-SMA) and a source of extracellular matrix (ECM). In this study, we investigated a potential link between inflammation and the growth process in human NPs. Sixteen patients who were affected by NPs and who had undergone functional endoscopic sinus surgery were included in this study. Nasal mucosa of inferior turbinate (NM) of 10 patients who had received rhinoplasty or turbinectomy for other disease was used as the control. alpha-SMA and TGF-beta 1 were detected using immunohistochemistry and the number of labeled cells were counted (alpha-SMA and TGF-beta 1 indices). The expression of alpha-SMA and TGF-beta 1 indices found in NPs and NM was compared using Student's t-test. In our study, alpha-SMA and TGF-beta 1 indices were found to be significantly higher in nasal polyps than in nasal mucosa. TGF-beta 1 produced by inflammatory cells can influence the development of myofibroblasts which in turn can induce extracellular matrix accumulation and, therefore, TGF-beta 1 plays a important role in the formation of nasal polyps.

Actins↗

PubMed2001

Inflammatory pseudotumor of the spleen--a case report.

A 36-year-old woman had suffered from epigastric fullness for half a year. A splenic mass was found by ultrasonography. She was treated with splenectomy. Inflammatory pseudotumor of the spleen was diagnosed pathologically. This benign tumor in the spleen is extremely rare. To our knowledge, only 67 cases had been reported in the literature. Recognition of this rare entity is important because it may mimic splenic malignancy clinically and radiographically.

Adult↗

PubMed2000

Nitric oxide mediates depressor responses by activation of N-methyl-D-aspartate receptors in the nucleus tractus solitarius of cat.

Nitric oxide (NO) is involved in cardiovascular regulation and sympathetic nerve activity of the central nervous system (CNS). The nucleus tractus solitarius (NTS) is important to cardiovascular regulation. However, the physiological role of NO in cardiovascular regulation effecting through the NTS remains unclear. The purpose of this study is to investigate the effect of NO measured by in vivo voltammetry on the cardiovascular responses in NTS induced by N-methyl-D-aspartate (NMDA) in anesthetized cats. Extracellular NO concentration was monitored through a Nafion- and porphyrin-coated carbon fiber electrode, which has previously been demonstrated sensitive and selective to NO responses. Microinjection of NMDA into NTS elicited a dose-dependent decrease in cardiovascular responses associated with NO release. Following the dose-response curve, a dose of 3 nmol of NMDA was selected. Microinjection of NMDA into NTS produced depressor responses and NO release. These responses in NTS to NMDA were attenuated by pretreatment with a competitive antagonist, 2-amino-5-phosphonopentanoat (AP-5, 1 nmol), and methylene blue (MB, 1 nmol), an inhibitor of guanylate cyclase. These results suggest that NO is formed from NMDA activation in NTS and that NO diffuses out of neurons into the nearby target neurons to produce depressor response and NO release through cyclic guanosine monophosphate (cGMP) formation. In conclusion, NO mediates depressor response consequent to activation of NMDA receptors in neurons of NTS.

2-Amino-5-phosphonovalerate↗

PubMed2000

Familial breast cancer in southern Taiwan.

The purpose of this study is to evaluate whether there are pathobiologic differences and differences in overall rates survival between familial and non-familial breast cancer patients in Taiwan. A retrospective study was performed evaluating 76 familial breast cancer patients in 69 families, which included two BRCA1 related cases and six BRCA2 related cases. Patients were compared with 425 non-familial sporadic cases. Familial breast cancer patients had similar ages and stages as non-familial patients (mean, 46.6 years vs 48.9 years, p = 0.306). However, the familial breast cancer patients with BRCA1 and BRCA2 related cases presented at lower stages (p = 0.034) and younger ages than non-familial patients (mean, 45.1 years vs 48.9 years P = 0.042). The occurrence of infiltrating ductal carcinoma and lobular carcinoma in situ was not significantly different in the two groups. Mucinous carcinoma was represented with 6.7% (4/76) and 1.3% (1/76) medullary carcinoma. The overall grade of familial breast cancer, including BRCA1 and BRCA2 related cases in 8 infiltrating ductal carcinoma, was significantly higher than that of controls. The mean follow up was 4.5 years for familial breast cancers. Five- and 10-year overall survival rates were 69% and 61% for those with a family history, compared with 86% and 64% for those in the control group (p = 0.644). There were no statistically significant differences in disease-free survival rates between the two groups at 5 or 10 years (69% vs 78% in 5 years; 48% vs 58% in 10 years) (p = 0.862). Despite the younger ages and earlier stages at presentation in familial breast cancer patients with BRCA1 and BRCA2 related cases, the familial breast cancer patients had higher grade patholobiologic characteristics, but similar prognoses when compared with sporadic breast cancer patients. Owing to the limited number of familial cases in this study, more cases and longer follow up are needed.

BRCA2 Protein↗

PubMed2000

Clinical significance of distribution patterns of P53 immunoreactivity in astrocytic tumors.

The difference of prognosis in patients with the same WHO grade of astrocytic tumors suggests that such tumors comprise a heterogeneous group in biological behavior. The correlation between p53 immunoreactivity and prognosis has often been reported but remains controversial. From the perspective of clonal expansion of p53 immunopositive cells, the distribution patterns of p53 immunoreactivity can be divided into four types: negative, scattered, focally clustered, and diffusely clustered. The survival rate was evaluated by classifying the p53 immunoreactivity into two groups: the significantly immunopositive patterns (focally and diffusely clustered types) and the significantly immunonegative patterns (negative and scattered types). The survival analysis showed a highly significant difference between these two patterns within the same WHO grade of astrocytic tumors (p = 0.0185). Our studies demonstrate that the distribution patterns of p53 immunoreactivity, which reflect the trends of clonal expansion of p53 immunopositive cells, are significantly valuable in predicting the prognosis of patients with the same WHO grade of astrocytic tumors.

Adult↗

PubMed1999

Correlation of vasomotor- and respiratory-controlling mechanisms around the caudal ventrolateral medulla in cats.

We examined the involvement of caudal ventrolateral medulla (CVLM) in respiratory control. Microinjection of glutamate (Glu) into CVLM decreased systemic arterial blood pressure (SAP) and altered phrenic nerve activities (PNA). Among 143 depressor sites, 55% (78/143) increased respiratory frequency (Rf), while 72% altered PNA amplitude (36% increased and 36% decreased). A small but significant positive correlation was observed between the magnitudes of depressor responses and inhibition of PNA amplitude (r = 0.1718, n = 143), indicating a substantial cross-talk between depressor and PNA inhibitory neurons. Furthermore, microinjections of acetylcholine (ACh) mimicked the Glu-induced depressor responses. However, ACh did not alter Rf, but still reduced PNA amplitude. Our findings suggest that Rf-regulating and depressor neurons are two separate neuronal populations, coexisting in CVLM. The PNA inhibitory and depressor neurons, in contrast, could have stronger correlation.

Acetylcholine↗

PubMed1999

Non-NMDA receptors mediate both pressor and depressor actions of the cardiovascular-reactive areas in the brainstem of cats.

L-glutamate (Glu), an important excitatory transmitter in the central nervous system, is mainly mediated via two kinds of ionotropic Glu receptors: N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA)/kainate (non-NMDA) receptors. Microinjection of Glu (0.1 M, 30 nL) into gigantocellular tegmental field (FTG), dorsomedial medulla (DM) and rostral ventrolateral medulla (RVLM) induced increases of the systemic arterial pressure (SAP) and the sympathetic vertebral nerve activities (VNA), while its microinjection into caudal ventrolateral medulla (CVLM) induced decreases of SAP and VNA. In this study, the 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA antagonist, was used to examine the effects of non-NMDA receptors on Glu-induced cardiovascular responses. Cats were anesthetized intraperitoneally with a mixture of urethane (400 mg/kg) and alpha-chloralose (40 mg/kg) and paralyzed with gallamine triethiodide (4 mg/kg, i.v. per hour). CNQX blocked the Glu-induced pressor responses in FTG, DM and RVLM but potentiated the depressor responses in CVLM. These results suggest that non-NMDA receptors modulate the central pressor and depressor responses in an opposite direction. On the other hand, activation of DM and RVLM neurons by application of AMPA (5 mM, 30 nL) evoked pressor responses. These AMPA-induced responses were significantly blocked by CNQX. Interestingly, CNQX itself induced pressor responses in many stimulated points of the pressor areas (FTG: 6/9; DM: 13/24; RVLM: 6/13), indicating a tonic release of Glu mediating depressor effects. In conclusion, non-NMDA receptors within the pressor (FTG, DM and RVLM) and depressor (CVLM) areas may play different modulatory roles in cardiovascular integration. The depressor mechanism mediated by non-NMDA receptors is tonically activated by the release of endogenous Glu in these pressor and depressor areas.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1999

Ultrasound effect on level of stress proteins and arthritic histology in experimental arthritis.

OBJECTIVE: To investigate the effect of ultrasound on the levels of stress protein in experimental arthritis and their relation to the therapeutic effects on arthritic cartilage repair. METHODS: Thirty-six rats with similar degree of early arthritis were divided at random into two groups. In group s, 18 rats received sonication; in group c, 18 control rats received sham sonication. The severity of induced arthritis was evaluated from bone scan with technetium-99m. The presence and changes of stress protein were identified from immunostain of SP72 antibody from frozen sections of arthritic cartilage and from electrophoresis of proteins extracted from chondrocytes of arthritic cartilage. The severity index, density of immunostained chondrocytes, and histopathologic changes at various periods were also studied in each group. RESULTS: The density of stress protein was increased markedly in treated rats after sonication and it was closely related to the repair of arthritic cartilage. Once the pathohistology of arthritic cartilage improved, stress protein declined significantly in the follow-up period. CONCLUSION: Therapeutic ultrasound can enhance stress protein production in arthritic chondrocytes. The extragenic production of stress protein was well correlated with the therapeutic effect of ultrasound to preserve chondrocytes and bring about the repair of arthritic cartilage.

Animals↗

PubMed1999

Expression and mutation analysis of the p53 gene in astrocytoma.

The role of p53 gene mutations in the formation or progression of human astrocytic tumors is controversial. We studied the distribution pattern of p53 immunoreactivity and analyzed p53 gene mutations to define the significance of p53 gene mutations in astrocytoma tumorigenesis or malignant progression. Twenty-three astrocytic tumors were evaluated with immunohistochemistry, single-strand conformation polymorphism (SSCP) analysis, and sequence analysis. We also searched MEDLINE to collect data on p53 gene mutation frequencies in astrocytic tumors in order to evaluate the association of p53 mutations and tumor grade. Strong immunoreactivity with a diffuse clustering pattern was found in three of five glioblastomas and seven of 12 anaplastic astrocytomas. Three of four low-grade astrocytomas were immunonegative. The p53 immunopositive cells in the only positively staining low-grade astrocytoma in our study appeared sparsely scattered. The results of immunostaining suggested that clonal expansion was associated with astrocytoma progression. Mutations of the p53 gene were detected in four of the 23 astrocytomas (one glioblastoma and three anaplastic astrocytomas). In the genetic data analysis, 76 of 367 astrocytomas had p53 gene mutations. A significantly greater p53 gene mutation frequency was found in anaplastic astrocytomas or glioblastomas than in the low-grade astrocytomas. The results of these immunohistochemical and genetic studies support the view that p53 gene mutation is associated with the malignant progression from low-grade to high-grade astrocytomas rather than with tumor initiation or promotion.

Adolescent↗

PubMed1999

Imaging features of simultaneous occurrence of renal and pancreatic foreign body granuloma due to chronically retained gauze: a case report.

Herein we are reporting a case of simultaneous occurrence of renal and pancreatic foreign body granuloma due to retained gauze. The different imaging features of the two lesions make correct preoperative diagnosis difficult. Foreign body granulomas due to retained surgical gauze or sponges should be considered in patients who have previous histories of operations and who also have a mass in the surgical bed. Simultaneous occurrence of foreign body granuloma away from primary surgical field is also possible.

Adult↗

PubMed1999

Brain tumors with hemorrhage.

Various types of brain tumors may cause hemorrhage. The purpose of the study was to examine the clinical relevance of tumor hemorrhage and the hemorrhagic mechanism from the pathologic viewpoint. We retrospectively reviewed 761 consecutive brain tumor cases according to clinical, operative, and pathologic records. Pituitary adenomas and recurrent tumors were excluded. Twenty-seven patients (17 men and 10 women, mean age, 50 years) with brain tumor hemorrhage were identified, resulting in an incidence of 3.5%. In 632 cases of primary brain tumors, there were 15 cases with hemorrhage, resulting in an incidence of 2.4%. There were 12 cases of brain tumor hemorrhage in 129 patients with metastatic tumors, for an incidence of 9.3% Among hemorrhagic cases, 63.0% of patients presented with acute onset of clinical deterioration. In 72.7% of gliomas with hemorrhage, hematoma appeared within the tumor, and 75% of metastatic brain tumors with hemorrhage were intracerebral hemorrhages around the borders of the tumors. The highest hemorrhage rate for primary brain tumors occurred in pilocytic astrocytomas, while the highest hemorrhage rates in secondary tumors occurred in metastatic thyroid papillary carcinomas and hepatocellular carcinomas. In our pathology study, increasing intratumor vascularization with dilated, thin-walled vessels and tumor necrosis were the most important mechanisms of hemorrhage.

Brain Neoplasms↗

PubMed1999

Evaluation of proliferative activity in middle ear cholesteatoma using proliferating cell nuclear antigen.

Middle ear cholesteatoma has a remarkable invasive activity accompanied by destruction of ossicles and temporal bone. Its aggressive growth and high tendency to recur have impact on the postoperative care of the patients. Proliferating cell nuclear antigen (PCNA) is a 36 KDa DNA-delta-polymerase-associated protein whose level of synthesis has been found to correlate directly with rates of cellular proliferation. In this present study, we used ABC (avidin-biotin complex) technique and monoclonal antibody to PCNA to evaluate the expression of PCNA in 37 cases of cholesteatoma epithelium and 21 cases of normal postauricular skin. The rate of PCNA-positive cells in basal, parabasal, and upper layer of cholesteatoma epithelium tissue is 78% (29 cases), 68% (25 cases), and 41% (15 cases). In each layer of the postauricular skin tissue is 71% (15 cases), 67% (14 cases) and 34% (7 cases). No statistical difference of expression of PCNA-positive cells exists between each layer of cholesteatoma epithelium and normal postauricular skin; however, a tendency of higher PCNA-positive cells in cholesteatoma epithelium was observed. Immunohistochemical method of PCNA has the advantages of spatial architecture preservation, the relative simplicity of the methodology and the rapid acquisition of results. Although the etiology and histopathology of the growth pattern and osteolytic activity of cholesteatoma are unclear, information on cell kinetics may assist in cholesteatoma classification and may help predict the risk of recurrence and bone destruction. The results of this report indicate that cholesteatoma has a similar proliferative activity to the normal postauricular skin, and cholesteatoma itself is not a real tumor, despite its clinical behavior, which is similar to neoplastic cells. It is necessary to further study whether the cell kinetic information we obtained from the PCNA immunohistochemical analysis provides a valuable tool in accessing the prognosis of the cholesteatoma.

Adult↗

PubMed1999

[Neural and hemodynamic mechanisms of neurogenic pulmonary edema].

Acute pulmonary edema has been reported in man and animals with intracranial disorders, head trauma or cerebral compression. In anesthetized rats, cerebral compression produced acute, fulminating and fatal lung injury. Intense activation of the sympathetic mechanism in the brain stem induced systemic hypertension and a series of hemodynamic changes. Pulmonary volume loading was the result of drastic decrease in aortic flow accompanying a decline in pulmonary arterial flow. The acute increase in pulmonary blood volume caused severe rises in pulmonary arterial and venous pressures leading to disruption of lung vessels.

Animals↗

PubMed1998

A single minute lesion around the ventral respiratory group in medulla produces fatal apnea in cats.

In 35 adult cats anesthetized with intraperitoneal chloralose and urethane, the ventrolateral medulla was explored by microinjection of kainic acid (KA, 24 mM, 200 nl) with metal electrode-tubing or glass micropipette to determine regions which elicit persistent apnea. Persistent apnea is defined as: (1) In spontaneously breathing cats, termination of respiration over 3 min with a decrease of the mean systemic arterial pressure (MSAP) to 25 mm Hg. (2) In animals under artificial ventilation and paralyzed by gallamine, cessation of bilateral phrenic nerve (PNA) activities over 25 min. The apnea producing area was located dorsal to the rostral pole of the lateral reticular nucleus, ventromedial to the ambiguous nucleus and immediately caudal to the retrofacial nucleus. Functionally, this region includes the rostral part of the ventral respiratory group (rVRG) encompassing the pre-BOtzinger area. We define this region as the VRG apnea producing area (VRG-Apa). Fatal apneusis was observed under following conditions: (1) Persistent apnea was produced after a single KA microinjection in one side of the VRG-Apa (5 animals). Microinjection of sodium glutamate (0.25 M, 70-200 nl) in the same area produced only brief apnea, while microinjection of kynurenic acid (0.1 M, 200 nl) showed little effect on the respiration but slightly increased the SAP. (2) Positioning an electrode nearby but not in the VRG-Apa with or without KA injection did not produce apnea. But when a second electrode insertion to the opposite VRG-Apa immediately produced persistent apnea even without KA injection (6 animals). (3) Midsagittal division of the medulla 0-5 mm rostral to the obex produced persistent silence of PNA on both sides in artificial ventilated animals (7 animals), while similar division 0-5 mm caudal to the obex (4 animals) produced a brief but reversible quiescence of PNA. In conclusion, findings of the present study support the existence of a restricted region of VRG-Apa. VRG-Apa on both sides are closely connected, and integrity of both VRG-Apa is essential for normal respiration.

Animals↗

PubMed1998

Attenuation of cardiac but not vascular component in baroreflex of spontaneously hypertensive rats.

The cardiac and vascular components of the baroreceptor reflex in spontaneously hypertensive rat (SHR) and stroke-prone spontaneously hypertensive rat (SHRSP) were compared against their counterparts in normotensive Wistar Kyoto rat (WKY). SHR, SHRSP and WKY of 12-16 weeks old were chronically instrumented for intra-arterial recording of blood pressure. Intravenous injections of phenylephrine and nitroprusside were used to challenge their baroreflex. The products of blood pressure change and the half time required for the pressure to return to the control value were used as the quantitative estimation of the blood pressure stabilizing capability. The cardiac component of the baroreflex was obtained from the change in the blood pressure stabilizing capability after blockade of beta and muscarinic receptors by atenolol and atropine, respectively. The vascular component was obtained by subtracting the cardiac component from the total stabilizing capability which was the difference after blockade with a ganglionic transmission blocker, hexamethonium. We found the cardiac component of the baroreflex of the hypertensive rats was significantly less sensitive than that of the WKY. In contrast, the vascular component of the baroreflex of the three strains did not differ significantly. Therefore, we concluded that the 12-16 week old SHRs were able to maintain a stable blood pressure due to the intact vascular component of the baroreflex.

Adrenergic alpha-Agonists↗