(-)和(+)棉酚对雄大鼠生育力的影响

Racemic, (-) and (+) gossypol, provided by the Department of Organic Chemistry of our institute, was suspended in 2.5% tween 80 solution. Adult male Wistar rats 190～220 g in weight were allotted to 5 groups. Animals in group 1 received 2.5% tween 80 solution as control. Rats in group 2 were treated with racemic gossypol at the dosage of 30 mg/kg for 2 weeks. Animals in group 3 and 4 were given 15 mg/kg of (-) gossypol for 2 weeks and 30 mg/kg of (-) gossypol for 1 week respectively. Rats in group 5 were treated with (+) gossypol at the dosage of 30 mg/kg for 2 weeks.Four weeks from the beginning of gossypol treatment the rats were cohabited with adult females for 7 days. Then the motility of the sperms in the cauda epididymides was estimated The female rats were examined for pregnancy 7 days later.Treatment with (-) gossypol at 30 mg/kg caused significant decreases in body weight of the rats (P<0.05). One of the five rats died 7 days after the last administration, while (+) gossypol and racemic gossypol at the dosage employed had no effect on the body weight. (+) Gossypol at 30 mg/kg for 2 weeks had no effect on the motility of the sperms in the cauda epididymides and no effect on the fertility of the animals: nor was there any effect on the weights of the testis, epididymis, prostate and seminal vesicle. The sperms of the cauda epididymides were found to be dead in the groups treated with 15 and 30 mg/kg of (-)gossypol. Raccmic gossypol given for 2 weeks at 30 mg/kg caused loss of fertility of the male rats which confirmed our previous findings.(?)t may be postulated that (+) gossypol has no antifertility effect nor toxicity at the dosage employed. (-) Gossypol is the active stereoisomer of racemic gossypol.     

醋酸棉酚对子宫和卵巢的影响

Gossypol has been employed in gynecologic clinics for the treatment of endometriosis and functional uterine bleedings with encouraging results. In the present communication the effects of gossypol on the uterus and ovary were studied both experimentally and clinically by histologic and histochemical techniques. It was found that treatment of female rats with gossypol acetic acid at 30 mg/kg/d, six days a week, for 8 weeks caused marked atrophy of the endometrium and a reduction of the glycogen content of the myometrium. Vaginal smears showed a picture of atypical estrous cycle. Simultaneous administration of 1 mg/kg/d of estriol reduced the effect of gossypol acetic acid though the influence of gossypol treatment was still discernible. Treatment of 16 patients suffering from endometriosis or functional uterine bleeding with gossypol acetic acid for 2-3 months induced changes similar to those observed in animal experiments, namely, atrophy of the endometrium and decrease in endometrium glycogen. In 3 other patients treated with gossypol acetic acid for 4～5 months there was a slight increase in Sudan Black B staining and a decrease in alkaline phosphatase, acid phosphatase, PAS staining and RNA of the endometrium. There was also a change of biphasic basal body temperature into monophasic and a lowered estrogen level as revealed by vaginal cytology.One may speculate from the above results that gossypol may act on the uterus directly as well as indirectly through inhibition of the secretory function of the ovary and/or through antagonism against the effect of estrogens in the female. Hence, it may be desirable to conduct further studies on the effect of gossypol on the pituitary-gonadal axis.     

Cardiovascular actions of Radix Stephaniae Tetrandrae: a comparison with its main component, tetrandrine

A comparison of the cardiovascular actions of the extract of Radix Stephaniae Tetrandrae (RST), the root of a Chinese herb Stephania tetrandra S Moore, in rats with those of tetrandrine (Tet), the best known active component of RST was reviewed. The RST extract inhibits Ca2 influx into the myocyte and reduces protein release during reperfusion with a Ca2 containing solution following perfusion with a Ca2 free solution (Ca2 paradox) , and arrhythmia during reperfusion in the isolated perfused heart. It also reduces the infarct size induced by ischemia/reperfusion in vitro and in vivo. In addition, the RST extract suppresses elevation of arterial blood pressure in DOCA-salt hypertensive rats. It does not further reduce the heart rate and coronary flow significantly during myocardial ischemia. The effects are similar to those of Tet. When compared with the same doses of Tet alone, the RST extract, of which 9 % is Tet, produces equally potent effects on infarction, arrhythmias, coronary flow and heart r     

肝细胞生长因子对长时间保存大鼠供体心bcl-2mRNA表达及细胞凋亡的影响

Objective To observe the effect of hepatocyte growth factor on isolated rat heart preservation. Methods Forty SD mrs were randomly divided into two groups : control group (n = 20) with isolated rat heart preserved in 4 ℃ HTK solution and experimental group(n =20) with isolated rat hearts preserved in 4 ℃ HTK + rh-HGF(100 μg/L) solution. Cell apoptosis was detected by TUNEL staining and the expression of bcl-2mRNA was examined by RT-PCR. Results Experimental group showed a lower rate of apoptosis eardiomyocytes (P < 0.01) after reperfusion. Immunohistochemieal analysis revealed that c-met receptor expression was stronger in the HGF-treated myocardium than that in the non-HGF-treated myocardium after storage and was associated with a stronger ex-pression of bcl-2 mRNA. Conclusion The administration of rh-HGF before storage improved cardiac function after prolonged myocardial preservation by preventing apoptosis and enhancing expression of bcl-2 mRNA.     

肝细胞生长因子对长时间保存大鼠供体心bcl-2mRNA表达及细胞凋亡的影响

Objective To observe the effect of hepatocyte growth factor on isolated rat heart preservation. Methods Forty SD mrs were randomly divided into two groups : control group (n = 20) with isolated rat heart preserved in 4 ℃ HTK solution and experimental group(n =20) with isolated rat hearts preserved in 4 ℃ HTK + rh-HGF(100 μg/L) solution. Cell apoptosis was detected by TUNEL staining and the expression of bcl-2mRNA was examined by RT-PCR. Results Experimental group showed a lower rate of apoptosis eardiomyocytes (P < 0.01) after reperfusion. Immunohistochemieal analysis revealed that c-met receptor expression was stronger in the HGF-treated myocardium than that in the non-HGF-treated myocardium after storage and was associated with a stronger ex-pression of bcl-2 mRNA. Conclusion The administration of rh-HGF before storage improved cardiac function after prolonged myocardial preservation by preventing apoptosis and enhancing expression of bcl-2 mRNA.     

肝细胞生长因子对长时间保存大鼠供体心bcl-2mRNA表达及细胞凋亡的影响

Objective To observe the effect of hepatocyte growth factor on isolated rat heart preservation. Methods Forty SD mrs were randomly divided into two groups : control group (n = 20) with isolated rat heart preserved in 4 ℃ HTK solution and experimental group(n =20) with isolated rat hearts preserved in 4 ℃ HTK + rh-HGF(100 μg/L) solution. Cell apoptosis was detected by TUNEL staining and the expression of bcl-2mRNA was examined by RT-PCR. Results Experimental group showed a lower rate of apoptosis eardiomyocytes (P < 0.01) after reperfusion. Immunohistochemieal analysis revealed that c-met receptor expression was stronger in the HGF-treated myocardium than that in the non-HGF-treated myocardium after storage and was associated with a stronger ex-pression of bcl-2 mRNA. Conclusion The administration of rh-HGF before storage improved cardiac function after prolonged myocardial preservation by preventing apoptosis and enhancing expression of bcl-2 mRNA.     

肝细胞生长因子对长时间保存大鼠供体心bcl-2mRNA表达及细胞凋亡的影响

Objective To observe the effect of hepatocyte growth factor on isolated rat heart preservation. Methods Forty SD mrs were randomly divided into two groups : control group (n = 20) with isolated rat heart preserved in 4 ℃ HTK solution and experimental group(n =20) with isolated rat hearts preserved in 4 ℃ HTK + rh-HGF(100 μg/L) solution. Cell apoptosis was detected by TUNEL staining and the expression of bcl-2mRNA was examined by RT-PCR. Results Experimental group showed a lower rate of apoptosis eardiomyocytes (P < 0.01) after reperfusion. Immunohistochemieal analysis revealed that c-met receptor expression was stronger in the HGF-treated myocardium than that in the non-HGF-treated myocardium after storage and was associated with a stronger ex-pression of bcl-2 mRNA. Conclusion The administration of rh-HGF before storage improved cardiac function after prolonged myocardial preservation by preventing apoptosis and enhancing expression of bcl-2 mRNA.     

The immunosuppressive effect of gossypol in mice is mediated by inhibition of lymphocyte proliferation and by induction of cell apoptosis

Aim： To investigate the immunosuppressive effect of gossypol in mice both in vitro and in vivo. Methods： The in vitro effect of gossypol on the proliferation of lymphocytes isolated from lymph nodes of BALB/c mice was determined by CFSE staining and by an MTS assay. Lymphocyte activation and lymphoblastic transformation were evaluated with immunostaining. Cell apoptosis was detected by Annexin-V and Hoechst 33342 staining. The in vivo immunosuppressive effect of gossypol on the DTH reaction was evaluated using a mouse DTH model induced by 2,4-dinitro-1- fluorobenzene （DNFB）. The thickness of the ears was measured, and the histological changes of the mouse auricles were observed after hematoxylin-eosin staining. The proliferation capacity of lymphocytes from DTH mice was also assayed. Results： In vitro, gossypol could significantly inhibit the proliferation of mouse lymphocytes stimulated with phorbol ester plus ionomycin in a dose-dependent manner. Although the expression of the early activation antigen CD69 was not affected, the lymphoblastic transformation of both T and B lymphocyte subsets was significantly suppressed by gossypol. Moreover, gossypol could induce apoptosis of lymphocytes, and the effect was time- and dose-dependent. In vivo, the DTH reaction in mice was markedly alleviated by gossypol injected intraperitoneally. Lymphocytes from drug-treated DTH mice had a reduced proliferation capacity as compared with lymphocytes from untreated DTH mice. Gossypol treatment also markedly reduced the number of infiltrated lymphocytes in the auricles of DTH mice. Conclusion： Gossypol exhibited immunosuppressive effects in mice, probably by inhibition of lymphocyte proliferation and by induction of cell apoptosis.     

Role of cyclic AMP in the prejunctional α2-adrenoceptor modulation of noradrenaline release from the rat tail artery

Summary Experiments were designed to evaluate the effect of cyclic AMP on the electrically-induced release of noradrenaline from vascular sympathetic nerve terminals. The possible implication of the inhibition of adenylate cyclase in the negative feed-back control by prejunctional α₂-adrenoceptors of neurotransmitter release was also investigated. Rat isolated tail arteries were preincubated with [³H]-noradrenaline; the preparations were subsequently perfused/superfused with [³H]-noradrenaline-free medium and their perivascular nerves were field stimulated with 24 pulses at 0.4 Hz (0.3 ms, 200 mA). 2 compounds known to enhance the intracellular concentration of cyclic AMP, namely the membrane permeant analogue 8-Br-cAMP (10–300 μmol/l) and forskolin (0.3–10 μmol/l), an activator of adenylate cyclase, concentration-dependently enhanced the stimulation-evoked tritium overflow. The 1,9-dideoxy derivative of forskolin, which does not stimulate adenylate cyclase, was ineffective. Exposure to the cyclic AMP phosphodiesterase inhibitor rolipram 30 μmol/l produced a moderate increase (about 20%) in tritium overflow. However, in the presence of rolipram the facilitatory effect of forskolin was significantly more pronounced than in its absence. Whereas 8-Br-cAMP produced a slight concentration-dependent enhancement of the stimulation-induced vasoconstriction, forskolin and rolipram depressed it. The α₂-adrenoceptor agonist B-HT 933 (3–30 μmol/l) concentration-dependently inhibited the tritium overflow. The effect of B-HT 933 30 μmol/l was slightly, but significantly reduced in the presence of 8-Br-cAMP 100 and 300 μmol/l, but was not changed in the presence of forskolin 3 μmol/l The facilitatory effect of rauwolscine 1 μmol/l was enhanced in the presence of 8-Br-cAMP 100 μmol/l. During perfusion with 8-Br-cAMP 100 μmol/l, the current strength and frequency were decreased to 150 mA and 0.2 Hz, respectively in order to obtain similar amounts of tritium overflow to those observed in the absence of the cyclic AMP analogue with the initial stimulation parameters. Under these conditions, the inhibition of the overflow by B-HT 933 30 μmol/l and the facilitation by the α₂-adrenoceptor antagonist rauwolscine 1 μmol/l were unaltered as compared to controls under initial stimulation conditions. It is concluded that, in the rat tail artery, the terminals of perivascular sympathetic nerves are endowed with an adenylate cyclase system. Cyclic AMP is able to modulate noradrenaline release, but does not appear to play a role in the initiation of the release process itself. In addition, the results do not support the hypothesis that prejunctional α₂-adrenoceptors depress noradrenaline release through the inhibition of adenylate cyclase. Send offprint requests to B. Bucher at the above address     

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores

We investigated the action of histamine on C6-astroglioma cells using patch clamp recording and intracellular calcium measurement. Application of 100 μM histamine hyperpolarized the resting membrane potential and increased free intracellular calcium. Membrane hyperpolarization was accompanied by a decrease in input resistance. The effect of histamine was reversible and responses persisted following repeated applications. In voltage clamp experiments histamine elicited an outward current associated with a conductance increase and a reversal potential near the Nernst potential for potassium. The action of histamine was blocked by mepyramine but not by cimetidine or thioperamide suggesting that a H₁ receptor mediated the response. Quinidine and charybdotoxin, but not apamin, blocked the hyperpolarization. Buffering internal calcium with BAPTA diminished the activation of the potassium channel, suggesting a calcium-dependent K⁺-channel, which was also found to be regulated by protein kinase C and phosphatases. The increase in intracellular calcium was not dependent on external calcium or sensitive to pertussis toxin, cholera toxin, forskolin or 8-bromo-cAMP. Both the hyperpolarization and the increase in intracellular calcium were blocked by thapsigargin or the phospholipase C inhibitor U73122. These results indicate that histamine liberates calcium from internal stores by activation of phospholipase C which in turn leads to an increase of intracellular Ca²⁺ and thereby to the activation of a calcium-dependent potassium channel in C6 glial cells. Received: 8 August 1996 / Accepted: 22 January 1997     

棉酚对大鼠钾代谢的影响和某些可能协同因子(低钾、低镁摄入)的作用

棉酚是一种颇有希望的男子节育药。临床试用表明,其效果良好,然而可偶致低血钾性肌无力症,后者是否与棉酚有关,尚无定论。虽离体实验表明,棉酚可使心肌失钾;但在整体动物,一般均认为,棉酚不影响钾代谢。我们在常规、低钾及低镁饲养大鼠,观察了不同剂量棉酚对细胞内、外离子(主要是钾、镁)、可交换钾、某些肾功能及其它一些方面的影响,结果表明: 在低钾饲养大鼠,大剂量棉酚可引起骨骼肌胞内钾、镁离子浓度普遍下降;在常规饲养动物,同量棉酚只引起个别肌肉胞内钾离子浓度下降。据此,可以认为,棉酚可影响钾代谢,而低钾摄入可能为棉酚所致钾代谢障碍的一个协同因子。在低钾饲养大鼠,小剂量棉酚可使半数肌肉的胞内镁离子浓度下降;大剂量则使所有受测肌肉的胞内钾、镁离子浓度下降,但此时血清钾不降,尿浓缩功能保持良好。凡此均提示,棉酚所致钾代谢障碍可能与镁代谢紊乱有关。大剂量棉酚可引起骨骼肌的萎缩性改变,表现在体重和肌重下降,尿中肌酐系数下降以及以身长为尺度的可交换钾量减少。     

Die Wirkung von Ouabain auf die Elimination von Noradrenalin aus der Perfusionsflüssigkeit des isolierten Kaninchenherzens

Summary Isolated rabbit hearts were perfused with Tyrode solution containing 10 ng/ml (-)-noradrenaline for 20 min. The uptake by the heart of noradrenaline was calculated by estimating the percentage of amine removed from the perfusion fluid during a single passage through the heart. Previous experiments have shown that the amount of noradrenaline removed from the perfusion fluid corresponds well to the amount retained by the heart.In control experiments, the mean removal (elimination) of noradrenaline was 50±1.7% of the amount infused as measured biologically and 46±2.2% as measured fluorimetrically. Ouabain was added to the perfusion fluid at concentrations ranging from 2.74·10^–7 to 2.0·10^–6 mol/l. The lowest dose caused a positive inotropic effect. With higher concentrations of ouabain there was a transitory increase in contractile force which was followed by a negative inotropic action, atrioventricular block and contracture of the myocardium. The noradrenaline uptake by the heart was neither affected by therapeutic nor by toxic concentrations of ouabain. On the other hand, almost complete inhibition of noradrenaline uptake was found after administration of 3·10^–5 mol/l cocaine.It is concluded that in the isolated heart ouabain does not interfere with noradrenaline transport across the cell membrane although the concentrations of ouabain employed are known to inhibit active transport of sodium and potassium.     

Inotropic and chronotropic effect of glycerol formal on the isolated rabbit heart.

Glycerol formal (CAS 5464-28-8), an organic solvent used to vehicle drugs to target cells, has been shown to possess its own toxicopharmacological properties. The present work was undertaken to study its direct effect on the isolated rabbit heart. At 2.3 and 4.6 mmol/l (bolus) glycerol formal exerted a positive inotropic effect. Upon a perfusion of 4.5 mmol/l/h, the left ventricular pressure and the coronary flow were increased, while at 11 mmol/l/h these two parameters showed a tendency to decrease. Glycerol formal upon a perfusion at 11 mmol/l/h decreased mildly the positive inotropic effect of noradrenaline, and strongly that produced by acetylcholine at a nicotinic dose, while it accentuated the bradycardia induced by acetylcholine at a muscarinic dose. On the contrary it potentiated the stimulant effect of nicotine. The positive inotropic effects of tyramine, dimethylphenylpiperazinium and potassium chloride were decreased showing an inhibition of noradrenaline liberation induced by glycerol formal at the doses used. The action of glycerol formal on agents inducing a positive inotropic effect, except nicotine, and its cardiodepressant effect are probably partly due to its action on the Ca2+ ion.     

Anti-arrhythmic effect of the sigma-receptor blocker DuP 734 in ischemia and myocardial reperfusion

It has been found that in vivo pretreatment of rats with the sigma receptor antagonist DuP 734 (1 mg/kg) resulted in an increase in the heart tolerance to ischemic and reperfusion arrhythmias both in vivo and ex vivo. Administration of DuP 734 (1 mg/liter) directly in the perfusion solution of isolated rat heart 10 min before total ischemia also promoted a decrease in the incidence of reperfusion arrhythmias. The normoxic perfusion of isolated rat heart at a dose of 1 mg/liter had no effect on the action potential. It was concluded that antiarrhythmic effect of DuP 734 might depend on the decrease in the Ca2+ overload but not on K+ and Na+ channel blockade.     

Environmental inhibition of 11beta-hydroxysteroid dehydrogenase

Gossypol, a polyphenolic compound from cotton seed, caused hypokalemia in some men receiving it in a trial of its contraceptive activity. Searching for the mechanism for its hypokalemic action led to the observation that it inhibited 11beta-hydroxysteroid dehydrogenase. This would enhance mineralocorticoid effect in the kidney. Many other polyphenols also inhibit this enzyme including those in grapefruit juice. Ingesting 1-2 l of grapefruit juice inhibited this enzyme in two men in a clinical experiment. Tea polyphenols inhibit this enzyme and add to the inhibition caused by gossypol. Men in China have lower serum potassium values than men elsewhere and this is due to the environment, presumably the diet, in China. The importance of dietary and other exogenous inhibitors of this enzyme in electrolyte metabolism remains to be determined.     

Comparison of potassium and adenosine cardioplegia with or without verapamil in the isolated guinea pig heart.

1. The cardioprotective effects of adenosine cardioplegia and classical potassium cardioplegia with or without adding verapamil were investigated in isolated guinea pig heart. 2. Four different cardioplegic solutions were used to arrest the hearts which were previously perfused by Krebbs-Henseleit solution. (A) potassium 20 mMol/l. (B) Potassium 20 mMol/l + verapamil 1 micromol/l. (C) Adenosine 10 mMol/l. (D) Adenosine 10 mMol/l + verapamil 1 microgram/l. 3. Both of the adenosine-containing solutions shortened the arrest time and maintained better postischemic recovery according to the potassium cardioplegia. 4. A rapid cardiac arrest was observed when verapamil was added to cardioplegic solutions, on the contrary there was no significant effect on postischemic recovery.     

ATP-sensitive potassium channel activation mimics the protective effect of ischaemic preconditioning in the rat isolated working heart after prolonged hypothermic storage

1. Ischaemic preconditioning (IP) can significantly reduce the extent of infarct size, contractile dysfunction and necrosis in hearts from a number of animal species. Activation of ATP-sensitive potassium channels has been implicated in this process. The aims of the present study were to determine the extent to which IP preserves haemodynamic function in the rat isolated working heart model after prolonged hypothermic storage and to examine the involvement of activation of potassium channels in this process. 2. Hearts from Wistar rats were perfused on a Langendorff apparatus. After stabilization in working mode, baseline measurements of heart rate, aortic flow, coronary flow and cardiac output were performed. Hearts were randomized to one of six treatment groups: (i) untreated control; (ii) IP; (iii) 3 min perfusion with 200 mumol/L pinacidil; (iv) pinacidil vehicle; (v) 3 min perfusion with 10 mumol/L glibenclamide before IP; and (vi) 3 min perfusion with glibenclamide then pinacidil. Hearts were stored in an extracellular-based preservation solution for 6 or 12 h at 2-3 degrees C, remounted on the perfusion apparatus, stabilized as before and then haemodynamic measurements were repeated, after which time heart water contents were determined. 3. Recovery of haemodynamic function was markedly enhanced in the IP and pinacidil-treated groups compared with untreated and vehicle controls. These beneficial effects were completely blocked by glibenclamide. These results suggest that strategies for activating potassium channels in donor hearts may protect organs during hypothermic storage prior to transplantation.     

Effects of potassium channel openers on single potassium channels in mouse skeletal muscle

Summary The patch-clamp technique was used to study the effects of the potassium channel openers cromakalim, pinacidil, RP 49356 and diazoxide on single potassium channels in mouse skeletal muscle.In excised patches in the inside-out configuration, one type of potassium channel, the ATP-sensitive potassium channel, could be activated by internally applied RP 49356 even in the absence of internal ATP. At a concentration of 0.4 and 0.8 mmol/l, RP 49356 increased the open-probability of the channels by a factor of 2.7 and 17.4 respectively. The stimulating effect of cromakalim (0.2–0.8 mmol/l) and pinacidil (0.4 mmol/l) depended on the presence of ATP (0.1 mmol/l) at the cytoplasmic side of the patch membrane. The two drugs were able to restore the open-probability of the channels blocked by internal ATP (0.1 mmol/l) to 50–90% of its value in ATP-free solution. No channel reactivation could be observed at a higher ATP concentration (1 mmol/l). Diazoxide (0.4 mmol/l) had almost no effect. None of these channel openers could stimulate the other prominent type of potassium channel in skeletal muscle, the large-conductance Ca²⁺-activated potassium channel.The results show that cromakalim, pinacidil and RP 49356 are specific openers of ATP-sensitive potassium channels in skeletal muscle. It is suggested that the drugs displace the channel blocker ATP and that RP 49356 in addition recruits inactive channels. Send offprint requests to B. Neumcke at the above address     

Inhibition of T-type Ca(2+) currents in mouse spermatogenic cells by gossypol, an antifertility compound

Gossypol, a male antifertility compound isolated from cotton, has been proved to inhibit capacitation and the acrosome reaction in human and mammalian sperm. Here, by using whole-cell recording, we observed the effects of gossypol on Ca(2+) and Cl(-) currents in mouse spermatogenic cells obtained by mechanical dissociation. The results showed that gossypol concentration-dependently and irreversibly inhibited T-type Ca(2+) currents in the cells. When the concentration of gossypol was > or =5 microM, the currents were blocked completely. The time to current block was progressively shortened as the gossypol concentration was increased from 5 to 80 microM. Moreover, the drug increased the time constant of inactivation in a concentration-dependent manner, while it did not affect the activation of the current. The inhibitory effect on the T-type Ca(2+) current did not correlate with signaling mediated by G proteins and tyrosine phosphorylation. No obvious effect of gossypol on Cl(-) currents was observed. These data suggest that the gossypol-induced inhibition of T-type Ca(2+) currents could be responsible for the antifertility activity of the compound, indicating a possibility to use gossypol as a local contraceptive drug.     

Effects of the novel calcium channel blocker,anipamil, on the isolated rabbit heart

Summary The calcium channel blocking activity of the novel phenylalkylamine derivative, anipamil, was tested on the isolated rabbit heart, in comparison with verapamil and gallopamil. Anipamil and the other calcium channel blockers lower left ventricular pressure in the same concentration range (10^–8 –10^–4 mol/1). The negative inotropic effect of anipamil is only partially reversed (nearly 65%) by rising calcium concentration in the perfusion fluid, whilst a complete recovery is observed for verapamil and gallopamil. The negative inotropic effect of anipamil is of rapid onset but long lasting, being still present 12 h after washout. On the contrary, that of gallopamil or verapamil completely disappears within 3 h of washout.Verapamil and gallopamil (10^–8 –10^–4 mol/1) depress spontaneous heart rate up to asystolia and abolish the vasopressin- and Bay K 8644-induced coronary spasm. Anipamil, on the contrary, does not modify coronary spasm elicited by both stimulants and spontaneous heart rate up to 10^–4 mol/l.These observations suggest that anipamil, in the isolated rabbit heart, possesses a peculiar pharmacological profile, since its calcium channel blocking activity is confined to the myocardial muscle.