Biomedical subjects

M Ishigami

Publications and source records attributed to M Ishigami.

At least 55 records · Page 3Linked to original sources

PubMed1995

Evaluation of the uptake of pravastatin by perfused rat liver and primary cultured rat hepatocytes.

PURPOSE: We have already demonstrated that the HMG-CoA reductase inhibitor, pravastatin is actively taken up by isolated rat hepatocytes via a multispecific anion transporter (Yamazaki et al., Am. J. Physiol. 264, G36-44, (1993)). We further attempted the quantitative evaluation of this uptake in different experimental systems. METHODS: We have quantified the initial uptake of pravastatin by both primary cultured hepatocytes and by isolated perfused rat liver using the multiple indicator dilution (MID) method. RESULTS: The permeability surface area product for the influx (PSinf) of pravastatin evaluated in MID study was comparable with those reported previously in isolated rat hepatocytes and in vivo. Furthermore, the highly concentrative uptake (influx clearance >> efflux clearance) of pravastatin was confirmed by kinetic analysis of the dilution curves obtained in the MID study. On the other hand, the uptake by primary cultured cells was significantly lower than that by isolated cells, and the ability of hepatocytes to take up pravastatin showed a decrease with time in culture (0-96 hr). The Vmax for uptake diminished with increasing time in culture, while no significant change was observed in both Km and nonspecific diffusion clearance. CONCLUSIONS: The MID method in isolated perfused liver which maintains the spatial and anatomical architecture can be used to quantitatively evaluate the initial uptake of pravastatin. Furthermore, the ability of hepatocytes to take up pravastatin is diminished in culture with time and this is caused by a decrease in Vmax.

Animals↗

PubMed1995

Decreased affinity of low density lipoprotein (LDL) particles for LDL receptors in patients with cholesteryl ester transfer protein deficiency.

We have reported that the disorder of lipoprotein metabolism in hyperalphalipoproteinaemic patients with a deficiency of cholesteryl ester transfer protein (CETP) is characterized by the polydisperse low density lipoprotein (LDL) particles and the accumulation of cholesteryl ester (CE) in high density lipoprotein (HDL) particles, forming cholesterol-induced HDL (HDLc)-like particles. In the present study we have investigated the interaction of these abnormal LDL with LDL receptors of normal human fibroblasts. Since the ultracentrifugally separated LDL fraction (1.019 < d < 1.063 g mL-1) from the CETP-deficient patients contained HDLc-like particles, these particles were removed by anti-apolipoprotein (apo) A-I immunoaffinity column chromatography. The lipoproteins eluted in the unbound fraction of this column did not contain apo A-I, so this fraction was considered to be authentic LDL. The authentic LDL of the patients were deficient in CE and rich in triglycerides and apo B. The authentic LDL itself showed polydispersity, ranging in size from 23 nm to 30 nm. The affinity of these abnormal LDL particles for LDL receptors was analysed by a competitive assay in which cold LDL from the patients or control compete with 125I-labelled LDL for fibroblast LDL receptors. The concentration of LDL particles at which 50% of 125I-labelled normal LDL was replaced was two to three times higher for the patients than for the normal control. Therefore, the affinity of patient LDL was thought to be reduced compared to that of control LDL. These results demonstrate that CETP may play an important role in making LDL particles homogeneous and rich in CE.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Angiotensin-converting enzyme polymorphism and development of diabetic nephropathy in non-insulin-dependent diabetes mellitus.

We determined the distribution frequency of angiotensin-converting enzyme insertion/deletion (I/D) polymorphism in 111 Japanese patients with non-insulin-dependent diabetes mellitus (NIDDM) of at least 10 years duration (80 patients with diabetic nephropathy and 31 patients without nephropathy) and 76 healthy Japanese controls. Patients with diabetic nephropathy showed an excess of the ID genotype compared with patients without nephropathy (p < 0.02) and less of the II genotype compared with healthy controls (p < 0.01) and patients without nephropathy (p < 0.01). NIDDM patients with the II genotype have a decreased risk for the development of diabetic nephropathy.

Adult↗

PubMed1995

Reduced uptake of oxidized low density lipoproteins in monocyte-derived macrophages from CD36-deficient subjects.

To clarify the physiological roles of CD36 as an oxidized low density lipoprotein (OxLDL) receptor, we analyzed the monocyte-derived macrophages from normal and two CD36-deficient subjects, since we identified the molecular abnormalities (Kashiwagi, H., Y. Tomiyama, Y. Kosugi, M. Shiraga, R. H. Lipsky, Y. Kanayama, Y. Kurata, and Y. Matsuzawa 1994. Blood. 83:3545-3552; and Kashiwagi, H., Y. Tomiyama, S. Honda, S. Kosugi, M. Shiraga, N. Nagao, S. Sekiguchi, Y. Kanayama, Y. Kurata, and Y. Matsuzawa. 1995. J. Clin. Invest. 95:1040-1046). Scatchard analysis of 125I-OxLDL binding showed a linear plot and the maximum binding was lower by approximately 40% in the macrophages from subjects with CD36 deficiency than those from normal controls. Competition studies showed that the uptake of 125I-OxLDL was suppressed by OKM5, an antibody against CD36, by 53% in normal control macrophages, but not in the CD36-deficient macrophages. After incubation with OxLDL for 24 h, cholesteryl ester mass accumulation was reduced by approximately 40% in the macrophages from CD36-deficient subjects than those from normal controls. These results suggest that CD36 is one of the physiological receptors for OxLDL. Since specific binding of OxLDL was only reduced by approximately 40% in spite of the complete deficiency of CD36, several other receptors also may have some role in OxLDL uptake. Further studies will be needed to assess the quantitative role of CD36 in foam cell formation in vivo.

Adult↗

PubMed1995

Effect of feeding clofibrate-containing diet on the hepatic NAD+ level in rats.

Feeding rats with a diet containing 0.25% clofibrate for 2 weeks elevated the hepatic NAD+ and total nicotinate levels significantly. Other peroxisome proliferators, such as 2-(4-chlorophenoxy)propionic acid and di(2-ethylhexyl)phthalate, had similar effects. When rats were fed the control diet without clofibrate for 1 week after 2 weeks of the clofibrate diet, the hepatic NAD+ level returned to the control value. Muscular NAD+ content was not affected by the peroxisome proliferators. The results were discussed in relation to induction of peroxisomal beta-oxidation enzymes by the peroxisome proliferators.

Animals↗

PubMed1994

Large and cholesteryl ester-rich high-density lipoproteins in cholesteryl ester transfer protein (CETP) deficiency can not protect macrophages from cholesterol accumulation induced by acetylated low-density lipoproteins.

High-density lipoprotein (HDL) has been speculated to have an anti-atherogenic function. Many in vitro studies have demonstrated that HDL has the ability to remove cholesteryl ester (CE) from lipid-laden macrophages. However, the effect of alteration in chemical composition and particle diameter on the in vivo function of HDL is unknown. In the study described here, we have isolated the HDL from patients homozygous for cholesteryl ester transfer protein (CETP) deficiency and examined its function in vitro, in order to clarify the anti-atherogenic property of HDL in CETP-deficient subjects. Apolipoprotein (apo) E-free HDL2 from the patients, separated by heparin-Sepharose column chromatography, was rich in CE, poor in triglycerides (TG), and enlarged in size on 4-30% nondenaturing polyacrylamide gradient gel electrophoresis. In contrast, HDL3 from the patients was normal in size and in its chemical composition. First, we examined the effect of HDL on CE accumulation in macrophages. After mouse peritoneal macrophages had been incubated with both acetylated low-density lipoproteins (Ac-LDL) and HDL, cellular CE content was determined by an enzymatic, fluorometric method. Ac-LDL alone induced a 9-fold accumulation of CE. The addition of apo E-free HDL2 and HDL3 from controls and patients' HDL3 prevented CE accumulation in macrophages, while patients' HDL2 had no preventive effect. We next investigated the in vitro ability of HDL to remove cellular CE from lipid-laden macrophages after incubation with Ac-LDL. After loading of macrophages with cholesterol by Ac-LDL, HDL was added to the culture medium and the cellular CE content was measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticholesteremic Agents↗

PubMed1993

Frequency of intron 14 splicing defect of cholesteryl ester transfer protein gene in the Japanese general population--relation between the mutation and hyperalphalipoproteinemia.

Cholesteryl ester transfer protein (CETP) deficiency, which has been found only in Japan, is characterized by marked hyperalphalipoproteinemia (HALP) and abnormalities of both low density and high density lipoproteins. We have reported that this deficiency is commonly associated with a G-->A mutation at the intron 14 splice donor site of the CETP gene (Yamashita et al., Biochem. Biophys. Res. Commun., 170 (1990) 1346-1351). In the current study, we determined the frequency of this mutation in Japanese subjects by using polymerase chain reaction. A single primer-template mismatch of one base pair from the CETP gene mutation permitted the introduction of a cleavage site for Nde I in mutant alleles but not in normal ones. Out of 171 patients with marked HALP whose serum HDL-cholesterol was more than 100 mg/dl, 6 (3.5%) subjects were homozygous and 48 (28.1%) were heterozygous for this mutation. Furthermore, in unrelated 512 healthy Japanese subjects, 5 (0.98%) were identified as heterozygotes. Relative allelic frequency of A at the intron 14 splice donor site was 0.0049 and the frequency of homozygous CETP deficiency was estimated to be approximately 1/42,000. These results demonstrate that this common mutation may be frequent in the Japanese population. Although HALP is very heterogenous, this mutation could be one of the major causes of marked HALP.

Alleles↗

PubMed1993

Protein-restricted diet prior to renal insult improves the recovery of renal function following ischemia.

The effects of a protein-restricted diet on renal recovery following renal ischemia were studied. The renal function was assessed by measuring the inulin clearance (CIN), the p-aminohippurate clearance (CPAH), and the percent fractional sodium excretion (%FENa) 24 h after 45 min renal ischemia. In rats fed with a regular diet (containing 19.6% protein), CIN was 10.0 +/- 2.2 microL/min/100 g body weight (BW), CPAH 0.08 +/- 0.02 mL/min/100 g BW, and %FENa 14.8 +/- 2.0, 24 h after renal ischemia. In contrast, feeding rats with a no-protein diet (0% protein) for 1 week prior to the ischemic insult significantly improved renal recovery (CIN 48.0 +/- 9.3 microL/min/100 g BW, CPAH 0.16 +/- 0.04 mL/min/100 g BW, and %FENa 2.43 +/- 0.58). Feeding rats with a no-protein diet for 3 weeks prior to ischemic insult further improved the renal recovery (CIN 113 +/- 30 microL/min/100 g BW, CPAH 0.47 +/- 0.17 mL/min/100 g BW, and %FENa 1.55 +/- 0.29). When rats fed with a regular diet were exposed to 45 min of ischemia, the survival rate on day 7 was 16.7%. In rats fed with the no-protein diet for 1 week and for 3 weeks, the 7-day survival rate was 100% in each case. The survival rate of rats fed for 3 days instead of 7 days with the no-protein diet was 87.5%. When a no-protein feeding was shortened to 1 day, no beneficial effects were observed and survival rate was 14.3%. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Beneficial effects of a non-protein diet on renal function of rats exposed to ischemic and nephrotoxic insults.

We investigated the effects of a non-protein diet on renal recovery in rats following 45-minute renal ischemia and mercuric chloride (3 mg/kg BW:S.C.) poisoning. The rats were fed a non-protein diet for one week before the renal insults. Renal functions were measured 24 hours after renal ischemia or 6 hours after mercuric chloride administration. In the ischemia investigation, the glomerular filtration rate (GFR), the renal plasma flow rate (RPFR) and the percent fractional sodium excretion (%FENa) of rats fed a regular diet (19.6% protein) were 25 +/- 7 microliters/min/g KW, 0.19 +/- 0.1 ml/min/g KW and 14.8 +/- 2.0, respectively. These values in the rats fed a non-protein diet showed better recovery, returning to a GFR of 114 +/- 32 microliters/min/g KW, an RPFR of 0.37 +/- 0.1 ml/min/g KW, and a %FENa of 2.43 +/- 0.6, respectively (p < 0.05). Furthermore, the seven-day survival rate was improved from 17% in the regular diet group to 100% in the non-protein diet group. In the mercuric chloride investigation, the renal functions in rats on a regular diet were shown by a GFR of 461 +/- 51 microliters/min/g KW, an RPFR of 1.91 +/- 0.2 ml/min/g KW, and a %FENa of 2.22 +/- 0.5. One-week feeding with a non-protein diet ameliorated the decrease in renal function, resulting in a GFR of 604 +/- 84 microliters/min/g KW, an RPFR of 2.15 +/- 0.5 ml/min/g KW, and a %FENa of 2.20 +/- 0.6. Consequently, there was a distinct beneficial effect on the survival of these rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Carrier-mediated uptake of pravastatin by rat hepatocytes in primary culture.

The transport mechanism of pravastatin, a new cholesterol-lowering drug, was compared in vitro with rat hepatocyte primary culture and mouse skin fibroblasts (L-cells). The uptake of 14C-labeled pravastatin by cultured hepatocytes was temperature- and dose-dependent. The temperature-dependent uptake as a function of [14C]pravastatin concentration showed saturation kinetics with Km = 32.2 microM and a maximal uptake rate of 68 pmol/mg protein/min. The uptake of pravastatin was inhibited significantly by metabolic inhibitors such as rotenone, oligomycin A, antimycin A, 2,4-dinitrophenol and KCN. Unlabeled pravastatin as well as R-416 and R-195, structural analogues of pravastatin, effectively competed for the hepatic uptake of [14C]pravastatin at 37 degrees. These results indicate that pravastatin is taken up by the liver by an active transport. In contrast, the transport of pravastatin by L-cells was temperature-independent and non-saturable, suggesting that the uptake of pravastatin by L-cells is mediated by passive diffusion. The marked difference in the uptake mechanism of pravastatin between hepatocytes and L-cells may account for a unique feature of this drug in that the uptake and inhibition of cholesterol biosynthesis occur selectively in the liver.

Animals↗

PubMed1991

Chronic alcoholism impedes the recovery of renal function following renal ischemia.

The recovery of renal function following renal ischemia was studied using rats fed for 1-, 3-, and 5-week periods with an alcoholic diet (ethanol provided 36% of total calories). Renal ischemia was produced by clamping the renal artery and vein for 20 min. Renal function was determined 24 hr after the ischemia. In the absence of ischemic insult, the renal function of rats fed with an alcoholic diet for 1, 3, and 5 weeks was not significantly different from those of nonalcoholic rats. In nonalcoholic rats, renal function (24 hr postischemia) were: glomerular filtration rate (GFR) 430.4 +/- 29.6 microliters/min/g KW (kidney weight), renal plasma flow rate (RPFR) 1.4 +/- 0.17 ml/min/g KW, and fractional sodium excretion (FENa) 2.0 +/- 0.04% (mean +/- SE). Postischemic renal function of rats on 1- and 3-week alcoholic diets were essentially the same as that of the control rats. However, the 24-hr postischemic renal function of 5-week alcoholic diet rats was significantly depressed. The values were only 117.2 +/- 35.2 microliters/min/g KW (p less than 0.05) for GFR, 0.31 +/- 0.12 ml/min/g KW (p less than 0.05) for RPFR, and 7.46 +/- 3.59% for FENa. The present results demonstrate that the rat kidney subjected to prolonged alcohol ingestion was more susceptible to renal insult than a nonalcoholic kidney.

Alcoholism↗

PubMed1991

Beneficial effects of the urinary trypsin inhibitor urinastatin on renal insults induced by gentamicin and mercuric chloride (HgCl2) poisoning.

The authors investigated the protective effects of the urinary trypsin inhibitor urinastatin on acute renal failure induced in rats by gentamicin (240 mg/kg body weight i.p. for 3 days) and by mercuric chloride (3 mg/kg s.c.). In rats injected with gentamicin, glomerular filtration rate (GFR), renal plasma flow (RPF), and percent fractional sodium excretion (%FENa) were 151 +/- 51 microliters/min/100 g body weight, 0.69 +/- 0.31 ml/min/100 g and 0.73 +/- 0.32, respectively, whereas in rats given 100,000 U of urinastatin the renal function was significantly ameliorated (GFR 318 +/- 43 microliters/min/100 g RPF 1.41 +/- 0.35 ml/min/100 g), although the %FENa (0.46 +/- 0.26) was not significantly improved. A 50,000-unit dose of urinastatin prevented the deterioration of renal function to some extent following administration of gentamicin: GFR 219 +/- 66 microliters/min/100 g and RPF 0.93 +/- 0.43 ml/min/100 g. In the study using mercuric chloride, treatment with 75,000 U of urinastatin protected the kidney from HgCl2 poisoning, yielding values of 294 +/- 93 microliters/min/100 g (GFR), 1.03 +/- 0.41 ml/min/100 g (RPF), and 1.44 +/- 0.72 microliters/min/100 g (%FENa) as compared with respective values of 169 +/- 48 microliters/min/100 g, 0.7 +/- 0.18 ml/min/100 g, and 2.22 +/- 1.35 in the untreated rats. Renal histology revealed mild to moderate tubular epithelial changes in untreated rats, but preservation of an almost normal tubular structure in urinastatin-treated rats in both studies.

Animals↗

PubMed1990

Actin cytoskeleton of resting bovine platelets.

Actin filaments in resting discoid bovine platelets were examined by fluorescence and electron microscopy. Rhodamine-phalloidin staining patterns showed a characteristic wheel-like structure which consisted of a central small circle connected by several radial spokes to a large peripheral circle. This wheel-like structure was composed of actin filaments forming a characteristic arrowhead structure with heavy meromyosin from muscle. Actin filaments were densely arrayed in parallel with a marginal microtubule band and radiated out from the center to the periphery. Platelets treated with colchicine lost their marginal microtubule band but retained their wheel-like structure and normal discoid form. Cytochalasin B disrupted the wheel-like structure but not the marginal microtubule band or the normal discoid form. After simultaneous treatment with both cytochalasin B and colchicine, platelets lost their discoid shape. These results suggest that actin filaments and microtubules both play important roles in the maintenance of the discoid shape of resting bovine platelets.

Actins↗

PubMed1990

Presence of four tachykinins in an acid extract of the carp intestinal bulb (Cyprinus carpio).

1. The pharmacological and chemical properties of substance P-like peptides isolated from an acid extract of the carp intestinal bulb were examined using guinea-pig ileum longitudinal smooth muscle. 2. On a Sephadex G25 column (3 x 96 cm), smooth muscle contracting material was eluted as two peaks (fraction-1 and fraction-2). The molecular weight of the fraction-1 was estimated to be 2300 and that of the fraction-2 to be 1530. 3. The pharmacological properties of the contracting materials in fraction-1 and fraction-2 resembled those of substance P and neurokinin A. 4. The susceptibility of the contracting activity of fraction-1 to proteolytic enzymes resembled that of physalaemin but, on the other hand, the susceptibility of that of fraction-2 resembled those of eledoisin and neurokinin A. 5. Ion-exchange chromatography on sulfopropyl-Sephadex C25 indicated the presence of one contracting material in fraction-1 and three contracting materials in fraction-2. The elution positions of four materials were different from that of substance P. 6. These results indicate that four tachykinins different from substance P are present in an acid extract of the carp intestinal bulb.

Amino Acid Sequence↗

PubMed1990

Do the H2-receptor antagonists, cimetidine and famotidine, modify the degree of renal recovery following renal insult?

The effects of two different H2-receptor antagonists, cimetidine and famotidine, on the acute renal failure induced by 20 min of renal artery occlusion and gentamicin (240mg/kg BW, s. c., for 3 days) were investigated in Sprague-Dawley rats. The animals were treated with either cimetidine (80 or 160 mg/kg BW) or famotidine (4 or 8 mg/kg BW) mixed in the drinking water for 7 days. The low dose of cimetidine and famotidine did not alter the renal function in the absence of renal trauma. However, the high dose of cimetidine or famotidine decreased the GFR by 32% and 22%, whereas RPFR increased by 46% and 62%, and % FENa by 92% and 558%, respectively. The data for the renal function obtained 24 hrs after 20 min of renal ischemia demonstrated a decrease of 54% in GFR, a decrease of 47% in RPFR and an increase of 370% in %FENa over the non-ischemic control values (p less than 0.05). Cimetidine (80 mg/kg BW) or famotidine (4 mg/kg BW) did not modify the recovery of renal function following the ischemic insult, showing 55% and 539% decreases in GFR, 74% and 101% increases in RPFR, and 393% and 461% increases in %FENa over the non-ischemic control rats, respectively. Famotidine reduced the decrease in RPFR significantly during the recovery period following ischemia. In the gentamicin study, gentamicin treatment was found to lower the renal function significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗

PubMed1989

Kidneys of chronic alcoholic rats are more vulnerable to ischemic insult.

The effects of chronic ethanol ingestion on the rat kidney were studied. Rats were fed a liquid diet containing ethanol for 5 weeks to induce chronic alcoholism. Renal ischemia was introduced by clamping the renal artery and vein either for 10 or 20 min. The glomerular filtration rate (GFR) and the renal blood flow (RBF) were determined by using I125-iothalamate and I131-iodohippurate. In the absence of renal ischemia, there were no significant differences in the renal function between nonalcoholic rats (n = 5) and alcoholic rats (n = 5): 380 +/- 30 vs. 403 +/- 27 microliters/min/100 g body weight (BW) in GFR, and 3.1 +/- 0.1 vs. 3.1 +/- 0.2 ml/min/100 g BW in RBF. The recovery of GFR measured 2 h following 10-min renal ischemia in both groups was not significantly different; the values returned to 340 +/- 40 microliters/min/100 g BW (nonalcoholic rats) and 246 +/- 22 microliters/min/100 g BW (alcoholic rats), respectively. The changes of RBF following 10 min ischemia were also similar in both groups. However, the effects of alcoholism on the renal function became apparent when animals were subjected to more prolonged renal ischemia. In nonalcoholic rats (n = 5), GFR and RBF measured 2 h following 20 min renal ischemia were 245 +/- 51 microliters/min/100 g BW and 2.5 +/- 0.4 ml/min/100 g BW, whereas in alcoholic rats (n = 5) the GFR and RBF were significantly decreased to 93 +/- 15 microliters/min/100 g BW and 1.1 +/- 0.2 ml/min/100 g BW, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗

PubMed1989

Effects of famotidine, a new histamine H2-receptor antagonist, on renal function.

The effects of famotidine on renal function were investigated. Eight healthy men (N) and 8 renal patients with varying degrees of renal failure (R.F.) participated in the trial. They were given either famotidine (40 mg) or cimetidine (800 mg) for 7 days. Cimetidine produced a significant decrease in creatinine clearance (from 131.6 +/- 12.9 to 107.7 +/- 3.4 ml/min (N), and 22.2 +/- 3.9 to 18.1 +/- 3.5 ml/min (R.F.], and increase in serum creatinine (from 0.96 +/- 0.05 to 1.09 +/- 0.04 mg/dl (N), and 3.46 +/- 0.62 to 3.86 +/- 0.51 mg/dl (R.F.], and a decrease in creatinine excretion (from 24.0 +/- 1.1 to 22.6 +/- 0.8 mg/kg/24 hr (N], respectively, although the reduction in creatinine excretion in the renal failure group was small. On the other hand, the famotidine treatment produced no significant changes in renal function in both subjects (creatinine clearance, 136.5 +/- 5.7 to 133.6 +/- 6.0 ml/min (N), and 21.9 +/- 3.6 to 20.9 +/- 4.1 ml/min (R.F.); serum creatinine, 0.98 +/- 0.02 to 0.99 +/- 0.02 mg/dl (N), and 3.24 +/- 0.43 to 3.46 +/- 0.55 mg/dl (R.F.); and urinary creatine, 25.1 +/- 1.0 to 25.3 +/- 1.0 mg/kg/24 hr (N), and 17.2 +/- 1.4 to 16.6 +/- 1.5 mg/kg/24 hr (R.F.]. There were no changes in the percent sodium excretion, or the serum and urinary beta 2-microglobulin in both groups.

Acetylglucosaminidase↗

PubMed1988

Evidence that a substance P-like peptide mediates the non-cholinergic excitatory response of the carp intestinal bulb (Cyprinus carpio).

The participation of substance P in the noncholinergic contraction induced by transmural stimulation (TMS) of the carp intestinal bulb was examined. In the presence of atropine, substance P caused the contraction of carp intestinal bulb smooth muscle in a concentration dependent manner (1 nmol/l - 1 mumol/l). The EC50 value was 28 +/- 7 nmol/l (n = 6). Substance P-induced desensitization (1 mumol/l for 15 min), decreased the response to substance P and the atropine-resistant contraction induced by TMS (20 Hz) selectively. In contrast, in the absence of atropine, the contraction induced by TMS (20 Hz) was slightly attenuated with the substance P-induced desensitization. The acid extract obtained from the carp intestinal bulb contained a smooth muscle excitatory material whose pharmacological properties were consistent with those of substance P. The present results indicate that a substance P-like peptide is present in the carp intestinal bulb which is involved in the non-cholinergic contraction induced by TMS.

Acetylcholine↗